ON THE HZEMATOZOAN INFECTIONS 
OF BIRDS 
by 
W. G. MacCALLUM, M. D., Johns Hopkins University 
From 
THE JOURNAL OF EXPERIMENTAL MEDICINE 
Vol. 111, No. i, 1898 ON THE HiEMATOZOAN INFECTIONS OF BIRDS. 
By W. G. MacCALLUM, M. D. (Johns Hopkins University) 
Plate XII. 
Onr knowledge of the nature of these infections, sometimes loosely 
designated as avian malaria, is mainly due to the researches of Danil- 
ewsky, Laveran, Kruse, Sakharoff, Grass! and Eeletti, Cell! and San- 
felice, Pfeiffer, Di Mattei, and Labbe. The only work upon this sub- 
ject so far done in America was reported in the papers on the etiology 
and pathology of haematozoan infections in American birds, read by 
Opie and myself before the Medical Society of the Johns Hopkins 
Hospital in November, 1896, and printed in brief in the Bulletin of 
the Johns Hopkins Hospital for March, 1897. These papers, which 
are published in full in the present number of this Journal (pp. 79 
and 103), give the results of observations made at the suggestion of 
Dr. Thayer of the Johns Hopkins Hospital, in the summer of 1896, 
on the blood and organs of various birds. 
During the past summer (1897) I have continued the work in 
Dunnville, Ontario, confining my attention mainly to crows, which 
seem to afford the most promising field for observation. 
Many species of birds have been found to be infected with these 
organisms to a greater or less degree—in Europe sparrows, finches, 
starlings, blackbirds, crows, hawks, etc. In Ontario and Maryland, 
where we have procured our birds, we have found sparrows, black- 
birds, owls and crows infected, and of these the crows were most fre- 
quently so, for although the number is too small to furnish any 
definite conclusions as to relative frequency of infection, some idea of 
this may be gained from the fact that of eighty sparrows the blood of 
five showed organisms, while of twenty-one crows sixteen were in- 
fected. 
The organisms in these cases are very similar in many respects to 
those found in the blood of human beings suffering from malaria. 118 
On the Haematozoan Infections of Birds 
There are, however, certain well-marked differences which I shall 
briefly review before detailing the results of my work of the past sum- 
mer. According to the observations of Labbe,* and those of Opie,f 
two types of organisms may be distinguished differing in form and life 
history as well as in the effects produced on the host. Of these the 
first, named by Labbe “ Halteridium,” begins its cycle of existence as 
a small oval or rounded hyaline body, situated laterally or at one end 
of the nucleus of the red corpuscle. As it increases in size it extends 
in a direction conditioned by the position of the nucleus, at the same 
time by its metabolic activity forming in itself granules of blackish- 
brown pigment. As it grows it extends more and more along the 
sides of the elliptical nucleus until finally, on reaching its adult stage, 
it is seen to coil about the nucleus, embracing it quite closely and ex- 
panding at each end into a wider portion into which the pigment, which 
increases with the age of the organism, is often gathered. Stained 
specimens show a tingeable cytoplasm in which the pigment is em- 
bedded and within which lies a clear non-stainable body with a 
central stained spot. This clear body is thought to be the nucleus 
with central nucleolus, and plays an important part in the process of 
segmentation as described by Labbe. He finds that the nucleus of 
the parasite divides into two segments, which separate and proceed 
to the ends of the organism, where they divide into multiples of two, 
thus forming two rosettes of segments lying at the ends of the red 
corpuscle. In the middle of the red corpuscles beside the nucleus 
there remains the pigment together with some debris of the organ- 
ism. Opie has not been able to confirm this observation, but has 
seen the formation of single rosettes in the bone-marrow, I have 
also found forms which might be designated as pre-segmenting in the 
circulating blood. In these the organism had rounded itself off in one 
end of the corpuscle, the pigment being gathered into a mass in its 
centre, the margin showing a number of indentations corresponding 
with which there were the fine refractive dots thought to represent 
the nuclear flecks in each segment. 
* Arch, de zool. exper., serie 2, 1894. 
t The present number of this Journal, p. 79. Chart I, showing Daily Temperature of a 
Normal Crow. 
Temperature Chart II of Crow infected 
WITH HaLTERIDIUM.* 
Flagellation almost identical with 
that observed in the case of the 
human malarial organisms is very 
readily seen in these organisms. The 
exact length of the cycle is very diffi- 
cult to determine, because all the or- 
ganisms present in the blood of any 
bird do not segment at the same time, 
nor even, so far as can be determined, 
in large groups, but at any time al- 
most all stages can be seen. Labbe 
places the cycle at seven to eight 
days. He, as well as I)anilewsky,f 
states that very little can be observed 
clinically in infections with this form 
of organism, although in the case of 
the second form about to be de- 
scribed, there are febrile symptoms 
with a certain rise in temperature. I 
have attempted to construct the ac- 
companying chart from a series of 
observations on the temperature of 
a crow infected with the Halter- 
idium and, although it does not ex- 
tend over any great length of time, 
it will serve to give some idea of the 
course of the temperature as com- 
pared with that of a crow which 
showed no infection. There is seen 
to be a daily rise of from 8 to 5 
* Kindly charted for me by Miss Hutchinson of the Training School for Nurses of the Johns 
Hopkins Hospital. 
t Arch. f. Ilyfj-i xxv (1895), 227. 120 
On the Haematozoan Infections of Birds 
degrees from the temperature recorded at midnight, and this, to a 
certain extent, is true of the normal crow, so that it can hardly he 
ascribed to the effect of the organisms, but we must perhaps rather 
consider the crow to be, to a certain extent, poikilothermic. 
There is, however, a rather higher temperature recorded on July 13, 
18, etc., suggesting that some group of considerable size might be seg- 
mented at intervals of five days. This, however, is not very constant 
and may have been accidental, although the blood on these days of 
high temperature seemed to show a larger percentage of hyaline forms. 
A variety of this Halteridium is found in the crow, blackbird, etc., 
in which the organism is much more slender, and when full-grown 
finds room to lie in the corpuscle without touching the nucleus. 
The second type of organism, named by Labbe “ Proteosoma,” also 
begins its cycle as a small, rounded or ovoid, hyaline body, generally 
situated near one end of the red corpuscle. As it grows, instead of 
accommodating itself to the position of the nucleus, it causes such a 
change in the stroma of the corpuscle that the nucleus no longer re- 
tains its central position, but is pushed to the opposite end of the 
corpuscle, where it comes to lie transversely. The pigment, which is 
on the whole finer and blacker than that of the preceding form, makes 
its appearance early and is distributed over the body of the parasite, 
which, in its adult stages, takes on a rounded or irregular polygonal 
form. Flagellation occurs precisely as in Halteridium. Segmenta- 
tion takes place in the circulating blood and results in the formation 
of a simple rosette with a central mass of pigment. As stated above, 
this form of infection seems to be accompanied by more serious clinical 
phenomena than the other. 
The Proteosoma I had no opportunity of observing during the past 
summer, and it is more especially of the Halteridium, which occurs so 
abundantly in crows, that I here wish to speak. The infections with 
the latter organism are generally relatively slight—one or two organ- 
isms being found in a slide of blood—and the birds may show no exter- 
nal evidence of being sick. There are other cases, however, where the 
bird can be recognized at a distance as being sick by its evident weak- 
ness, its uncertain flight and altered voice, as well as its draggled ap- W. G. MacCallum 
121 
pearance and lustreless plumage. Such birds often show an enormous 
infection, at times more than a third of the corpuscles being invaded, 
with sometimes two or even three parasites in a single corpuscle. They 
may, however, recover to a certain extent in confinement when well 
fed, and the organisms may be seen to diminish in number most mark- 
edly. 
On examining a slide of fresh blood where the organisms are numer- 
ous, examples of flagellating forms are observed with extreme readiness 
about two and a half minutes after the blood has been taken from 
the bird (Plate XII, Fig. 6). This process, accurately described by 
most authors on the subject, takes place as follows: The adult organism 
is seen to draw itself together into a sphere within the red corpuscle, 
and sometimes immediately, but more often after a short delay, it be- 
gins to be greatly agitated, the pigment dancing about and the surface 
of the sphere taking on an active undulating motion which lasts but a 
short time, for the organism suddenly bursts from the corpuscle, scat- 
tering the remains of the latter, and in its place beside the nucleus of 
the corpuscle, which now lies free in the plasma, it throws out four or 
more flagella, which thrash about wildly and sooner or later become 
detached and wriggle away. The sphere is much reduced in size by 
this throwing out of flagella and the pigment is concentrated, although 
occasionally a pigment grain is included in one of the flagella, which 
are not perfectly regular in form, but may branch or run into one 
another at the base. Their number is not constant and may change in 
the process of their formation. The remains of the sphere continue to 
be agitated and, after the loss of the flagella, its pigment sets up 
a most active dancing. Often it constricts itself into two or more 
parts, which may reunite, and sometimes a more than usually stout 
prolongation of protoplasm, which has failed to become a perfect 
flagellum, may adhere and beat about for a long time. Disintegra- 
tion and death are the inevitable fate of these remains of the flagellate 
body, even if it escapes for any length of time one of the voracious 
leucocytes which wander about. 
There is a certain variation in the relation of the act of throwing 
out flagella to the extrusion from the corpuscle. At times the organ- 122 
On the Haematozoan Infections of Birds 
ism can be seen to throw out flagella while still within the corpuscle, 
these beating the nucleus about within the enveloping membrane of 
the corpuscle, which is violently agitated and distorted like a loose bag 
containing the struggling organism. At last the membrane bursting 
liberates the fully developed flagellate form. In other cases the 
sphere slowly escapes through a rent in the capsule, and after a period 
of quiescence outside the corpuscle, begins to be agitated and finally to 
put forth its flagella. 
Other organisms escaping quietly in this way through a rent in the 
capsule remain quiescent and never become flagellated (Plate XII, 
Pig. 5). 
There is always in these processes the escape of the remaining 
haemoglobin of the corpuscle into the plasma, with a corresponding 
blanching of the corpuscle and, although the thin capsule is left for a 
time, it soon becomes invisible. 
Many theories as to the nature of these flagellated forms and the 
significance of the process have been put forward, none of which have 
met with general credence. Laveran thought the flagella were pre- 
existent in the body of the intracorpuscular parasite. He believed the 
flagellate forms of the human malarial organism to be the final and 
most perfect stage of the parasite, and that they developed within the 
round and crescentic bodies which he regarded as cysts. Hock consid- 
ered that they represented a resting stage of the organism capable, of 
existing independently, perhaps even of reproducing themselves, but 
also capable under favorable circumstances of reproducing a typical 
growth of the parasite. Mannaberg suggests that they are organs 
which permit the parasite to enter into a saprophytic existence. “ I 
suspect,” he says, “ that the flagellate bodies enter upon the first 
stages of a cycle of existence outside of the human body, and that as a 
result of the unfit culture medium the death of the young spores 
occurs.” The whole Italian school believes them to be due to degen- 
erative changes. Manson, as is well known, has advanced the idea 
that the flagellate bodies represent the forms in which the parasite 
exists outside the human body, that the flagella penetrate from the 
stomach into the body of mosquitos which have sucked the blood of W. G. MaeC album 
123 
infected human beings, and that, after a further unknown process of 
development, they come again, through the water in which the mos- 
quitos deposit their eggs and die, into the human body. Sakharoff 
recognizes the flagellate bodies as dying forms; he finds the large red 
nucleus (with Eomanowsky’s stain) with a, clustered chromatic fila- 
ment. In the free forms this last breaks up into several filaments, 
which leave the parasite as flagella—a perversion of karyokinesis 
which is provoked by physico-chemical means. Zacharias claims to 
have produced flagella in epithelial cells by the action of phosphoric 
acid, and Labbe gives it as his opinion that the process of flagellation 
resembles a chemical one, that lack of oxygen hastens the process, 
as also does the sudden drop in temperature from 42 to 15 degrees C. 
Flagellate forms, he concludes, are abnormal agony products preceding 
degeneration, which do not exist in the living blood, but form outside 
the body under the diverse physico-chemical influences which modify 
the plasma and corpuscles obtained from the vessels. 
It will be seen that none of these ideas, except that of Sakharoff, are 
based on any observations, but are for the most part pure hypotheses. 
That the flagellate forms are the agony products of the dying para- 
sites seems to be the most generally accepted idea,, and this, it is true, 
has the fact to support it that it occurs only under unfavorable circum- 
stances, and is followed by the death of the organisms. 
Other motile bodies have from time to time been described as occur- 
ring in the blood of birds. Danilewsky* describes elongated non- 
pigmented organisms found in fresh blood plasma. These are seen to 
swell and contract and frequently to advance in a curved or spiral 
line. He thinks they are related to the Drepanidia, but Labbe sug- 
gests with more probability that they are free flagella. 
In addition to these Danilewsky also describes an organism resulting 
from the transformation of an intra-corpuscular pigmented form. 
This becomes extra-corpuscular and spherical and, after the lapse of 
ten to thirty minutes, a process appears at the periphery of the body 
which, increasing in size, gives rise to a curved elongated body which 
he calls a vermiculus. This body, which has acquired a nucleus, 
Danilewsky, Parasitologie comparee du sang. Tvharkow, 1889. 124 
On the Haematozoan Infections of Birds 
moves about in a curved line in the plasma. Kruse * described a sim- 
ilar form in the blood of a crow, and Pfeiffer fin that of an owl. Xo 
further idea as to their nature was given. 
It was noted by Opie (p. 92) that there were variations in the adult 
form of the Halteridium, which I have endeavored to depict in Plate 
XII, Pigs. 1 and 2 and Figs. 3 and 4. This difference, which sharply 
distinguished two forms of the organism, consisted in a granular ap- 
pearance in the one as compared with the clear hyaline protoplasm of 
the other forms. The protoplasm in the first form was not simply 
finely granular, but in a groundwork of finely granular protoplasm 
could be seen minute hyaline points. This difference was much more 
sharply brought out by staining with methylene blue when the granu- 
lar form took on a deep stain, the fine granules especially appearing 
dark blue while the hyaline points remain wholly unstained. The 
hyaline form, on the other hand, took almost no stain, the slight tinge 
of blue being for the most part peripheral, sometimes with a blue 
fleck in the centre of the unstained portion. The pigment granules 
are, as a rule, finer in the granular forms than in the clear hyaline 
forms. 
Opie (p. 96) put forward the suggestion that it might be these clear 
non-staining forms which become flagellated, the granular forms be- 
ing the ones observed to degenerate without flagellation. 
My observations have enabled me to confirm this distinction, and to 
demonstrate that it is true that the granular forms never become 
flagellated and that the clear forms alone do so. Indeed, it may be 
prophesied of any organism while yet intra-corpuscular that it will or 
will not become flagellated. 
While watching one of these specimens which had stood for some 
time I was surprised to see an elongated organism moving slowly 
across the field followed by others moving in all directions. These 
were evidently modifications of the organism familiar in fresh speci- 
mens, and the question of greatest interest was to show their relation 
to the other forms. They corresponded very closely with the vermi- 
* Kruse, Virchow’s ArcMv, cxx (1890), 541, and cxxi, 359. 
f Pfeiffer, Zeitschr. f. Hyg., viii (1890), 309. W. G. MacCallum 
125 
culi of Danilewsky, and I have assured myself since that they are 
identical with them. 
As the forms which flagellated were always observed to disinte- 
grate or succumb to a leucocyte, the idea, remained that the motile 
forms might arise from the forms described as being extruded from 
the corpuscle without flagellation. On carefully watching these for 
fifteen to twenty minutes it proved to be easy to see the change from 
the non-motile sphere into the motile elongated organism or vermi- 
culus. In one or two instances, however, it was noted that such non- 
motile spheres apparently became flagellated Avithout the extreme 
agitation usually seen in the process of flagellation, and without any 
diminution in their bulk, and later on gave rise to the motile forms. 
This seemed to contradict the idea that these arose exclusively from 
the non-flagellating forms, and apparently there remained the conclu- 
sion that flagellation was a process which proceeded more or less vio- 
lently in different cases; that where the violence was great the store 
of energy of the organism was exhausted; where, however, it did not 
take place, or took place in such a modified and mild form that not 
much energy was expended, the organism was able to take on a motile 
form. 
I decided, however, on the impulse of another idea, to observe care- 
fully in the same field a granular form and a hyaline form from the 
time of extrusion from the corpuscle to the beginning of the motile 
stage, and, having found such a field, the following picture presented 
itself: The two forms lay at some distance from one another separated 
by the plasma and a few corpuscles. The granular form happened to 
escape from the corpuscle first and lay perfectly quiet beside the free 
nucleus and the shadow of the corpuscle. Soon the hyaline body, 
becoming greatly agitated, burst from the corpuscle and threw out 
active flagella, which beat about for a few moments and finally tore 
themselves loose. Then came the acme of the process. One of the 
four flagella passed out of the field, but the remaining three proceeded 
directly toward the granular form, lying quietly across the field, and 
surrounded it, wriggling about actively. One of the flagella, concen- 
trating its protoplasm at one end, dashed into the granular sphere, 126 
On the Haematozoan Infections of Birds 
which seemed to put out a process to meet it, and buried its head, 
finally wriggling its whole body into the organism, which again became 
perfectly round. The remaining flagella, seeking to repeat tins pro- 
cess, were evidently repulsed, and soon became inactive and degen- 
erated. Immediately on tire entrance of the flagellum the pigment of 
the organism was violently agitated, without, however, any disturb- 
ance of the outline of the organism. Soon all became quiet again and 
the jieriod of quiescence lasted for about fifteen minutes, when a coni- 
cal process began to appear at one margin of the organism, which, in- 
creasing in size, drew into itself most of the protoplasm, the pigment to 
a certain extent being gathered into the remainder. Finally most of 
the pigment was concentrated into a small round appendage, which re- 
mained attached to the end of what now had became an elongated 
fusiform body, which soon swam away with a gliding motion. 
Have we not here, without much doubt, a sexual process in the 
organisms the result of which is the motile vermiculus? This is a 
process which we might have expected and which I am confident will 
be found to occur in the case of the human malarial parasites, although 
on account of the small number of organisms to be found in each slide 
in the latter case, the completion of the process will rarely be observed. 
It is entirely analogous to the sexual process as it occurs in the lower 
plants under unfavorable conditions. In Spirogyra and other related 
algae, when their circumstances have become such that the ordinary re- 
production by fission can no longer result in the successful prolongation 
of life, a more resistant body is formed by the conjugation of the adja- 
cent cells of two filaments; but so long as conditions of growth are 
favorable we look in vain for this process. A similar conjugation is 
observed in many of the Ascomycete fungi and many other plants. 
In the animal kingdom we find it again and again, and I need only 
mention the pond Amoeba as a familiar example.* 
* Since the communication of this paper to the British Association for the 
Advancement of Science in Toronto on August 34, 1897, I have been much 
interested in the perusal of the article by Simond (Annates de VlnstitiU 
Pasteur, July 25, 1897, p. 545), in which he describes in certain coccidia a 
process analogous to that described here and suggests the probability of the 
occurrence of a sexual process in the malarial organism. W. G. MacCallum 
127 
We can thus consider the two forms of adult organism found in the 
fresh blood as male and female, the granular female form containing 
more chromatophilic substance than the hyaline male form, which we 
may now say gives up its life in the production of four or more sper- 
matozoa or flagella. Now, too, the mistake of thinking that the 
motile forms might arise from organisms in which the process of 
flagellation had proceeded less violently, is easily explained. Such 
organisms were simply the spherical granular forms surrounded by 
spermatozoa or flagella, which had arrived from the neighboring true 
flagellate forms and were undergoing the process of fertilization. 
In view of all this it seems to me that we must look on the observa- 
tions of Sakharoff with more confidence than has been accorded them 
by authors in general. Although I have stained with an excess of 
gentian violet the free flagella in the plasma and surrounding female 
spheres, I have not been able so far to confirm his statements by the 
application of staining reagents, but I feel assured that, were such 
nuclear staining successfully carried out, we should see in all essentials 
his clustered chromatic filament which, on breaking up into several 
filaments, forms, each with a certain amount of protoplasm, several 
flagella. His ideas as to the cause of the process are rather more 
hypothetical. 
To return to the organism, immediately after fertilization, a process 
which when once recognized I have observed daily, it seems clear that 
the agitation of the pigment on the entrance of the flagellum is due 
merely to the mechanical motion of the wriggling flagellum, for it 
quiets down very soon. From this point on for ten to fifteen minutes 
it seems probable that, with suitable nuclear stains, one might demon- 
strate the coalescence of male and female nuclei, but I have not as yet 
done so. After a lapse of fifteen to twenty minutes the organism be- 
comes motile, as above described, by the passage of the protoplasm into 
a conical process (Plate XII, Fig. 8), which gradually enlarges so as 
to contain the whole organism with the exception of a small spherical 
appendage into which most of the pigment is crowded (Plate XII, 
Fig. 9). The organism now appears quite fusiform, or at times egg- 
shaped, or even almost spherical, the anterior small end being free 128 
On the Ilaematozoan Infections of Birds 
from the pigment, which is distributed quite superficially over the 
posterior part. Toward the anterior part, hut sometimes quite in the 
middle of the organism, there lies a fairly definite nucleus with well- 
marked nucleolus. This nucleus does not stain sharply, hut is quite 
readily seen in fresh specimens, although no structure so definitely 
marked off hy its different refractive index was observable in the 
adult male and female forms of the organism. The protoplasm re- 
tains the characteristic granular appearance seen in the female form. 
Occasionally in beginning its movements away from the nucleus of 
the red corpuscle the organism leaves behind it part of the pigmented 
appendage—or it may possess two of these spherical appendages at- 
tached one behind the other, and in starting leave one of these behind 
to be broken down or engulfed by a leucocyte. The movement has 
nothing of the character of that of the flagellate forms, but is slow and 
even, the organism progressing invariably with the pointed end, free 
from pigment, forward. It can move in any direction readily, curv- 
ing about obstacles and passing accurately between groups of corpus- 
cles. Often it is seen to rotate continually on its long axis, at which 
times the superficial position of the pigment is readily seen. This rota- 
tion does not seem, however, to be in any way necessary to the forward 
motion. Again a third form of motion is observed in that a sort of 
peristaltic wavy constriction may repeatedly pass from anterior to pos- 
terior end of the organism, giving rise to very considerable distortions. 
The forward progression of the organism occurs with very consider- 
able force, as one may often be seen to thrust aside a group of red cor- 
puscles. More often, however, they push directly through the ob- 
stacle, and it is interesting to observe that they can and do dash 
through the body of a leucocyte, tearing it apart, scattering its refrac- 
tive grannies into the plasma and often dividing its nucleus into two 
parts, thus leaving it to disintegrate. Passing on unharmed they at- 
tack masses of red corpuscles and leave those in their path as shadows 
of which soon only the nucleus is visible. This blanching of the cor- 
puscles seems to become possible to them by the merest touch of their 
anterior pointed ends, which apparently puncture the capsule of the 
corpuscle and allow the haemoglobin to escape into the plasma. Indeed, W. G. MacCallum 
129 
in a thick slide of blood, a single organism may circle about and clear 
for itself a very considerable space in which there remain only shadows 
with the nuclei of corpuscles, and in some of the intense infections, 
which I have referred to, every slide of blood, after standing from 
thirty minutes to an hour, will show nothing but shadows, the organ- 
isms, very young and half-grown forms as well as segmenters, being 
often left free in the plasma. On one or two occasions these forms 
have been seen to put out pseudopods which attacked the corpuscles 
in a similar way. 
In passing through a group of corpuscles it is frequently observed 
that the posterior end of the moving organism adheres to the corpus- 
cles, and it may often be seen dragging three or four behind it. These 
soon become detached, however, and fall back, sometimes greatly 
distorted. In other cases the organism adhering to the corpuscle may 
draw out its capsule into a process, which gradually sinks back when 
the organism breaks away. 
The ultimate fate and the true significance of these motile forms is 
difficult to determine, for in a slide, after being watched for more than 
one or two hours, the conditions become such that conclusions can 
scarcely be drawn as to the result under less artificial circumstances. 
Simple quieting down and final disintegration seem to be the end of 
many, but in some cases the organism was seen suddenly to stretch 
itself out by jerks into a greatly elongated form, sometimes dividing 
into segments connected by a fine thread. Generally in such cases the 
clear anterior end became separated from or connected only by a 
thread with the rest (Plate XII, Fig. 10), and often finally swam 
away by itself, leaving the rest to the leucocytes. This clear portion, 
however, was never seen to accomplish anything other than disin- 
tegration, although it was often watched with the idea that it might 
enter a corpuscle and set up a new cycle of existence. 
It seems to me most reasonable to suppose that the motile form is 
the much sought resistant stage, or perhaps the first step in the pro- 
duction of such a stage. It seems probable that by the aid of such 
powerful means of locomotion and penetration it might make its way 
through a considerable obstacle of tissue to gain a new medium. This 130 
On the Haematozoan Infections of Birds 
of course might occur in several ways in the dead body subject to ex- 
ternal violence. But in no case which I have examined post mortem 
did the organisms show any signs of life after the lapse of two to three 
hours, although the blood was still perfectly fluid in the vessels. In 
the living body, however, it seems that the intestine would form the 
most ready means of escape, and accordingly search Avas made in the 
faeces for such forms. In the birds at my disposal, however, in some 
cases the infection was so slight that results could hardly be expected, 
and in the cases where the infection was large, the presence of numer- 
ous echinostomes in the rectum rendered the mode of entry of the 
abundant blood corpuscles and organisms into the intestine doubtful. 
In dried smears from the contents of the small intestine, however, 
free organisms, free malarial pigment and one intra-corpuscular or- 
ganism were found. More certain data might be expected from sec- 
tions of the intestine with its contents, and examination of such sec- 
tions showed immense numbers of organisms, mostly intra-corpus- 
cular but sometimes extruded, in the capillaries of the stroma of the 
intestinal mucosa. In the mucous contents of the intestine were 
numerous free organisms, several of which exhibited the form de- 
scribed above as characteristic of the motile stage. The fact that the 
organisms were lying quite free in mucus, and that no corpuscles or 
nuclei of corpuscles were found, argues in favor of the idea that these 
organisms penetrated the mucosa after extrusion from the corpuscle. 
ISTo organisms were found on the waj through the epithelium. The 
inference that the organisms escape thus from the body seems plain, 
and further examinations of the intestinal contents obtained fresh 
immediately after death would be interesting. 
In concluding this portion of the paper I may be allowed briefly to 
summarize what I have said. 
Two types of organism occur so far as is known in the hlood of birds. 
Minute morphological descriptions of these have been omitted in this 
paper. In the adult stage of one of these (,Halteridium) there are cer- 
tain differences between two forms ivhich are thought to be sexual 
differences. Of these forms, one on extrusion from the corpuscle lies 
quiet and is soon approached and fertilized by a “ flagellum ” pro- W. G. MacCallum 
131 
duced by the other form on extrusion from the corpuscle. The result 
of this fertilization is a motile stage which seems more resistant, and it 
is thought possible, in view of certain facts, that this form may make 
its way through the intestinal canal to the external world. 
Reasoning by analogy it is thought very probable that the signifi- 
cance of the flagella in the human organism is similar to that given 
here for the organism of the birds. 
THE PATHOLOGY OF HAEMATOZOAN INFECTIONS OF BIRDS. 
The literature on the pathology of luematozoan infections is very 
meagre indeed. Danilewsky * speaks of the changes in the spleen and 
bone-marrow and describes macrophages with their varied contents. 
Kruse f made similar observations as to the spleen, bone-marrow, liver 
and lung, and Labbe % also speaks in a general way of the gross 
changes in the organs. In the preceding paper on the subject, in 
this Journal (p. 103), prepared a year ago, I have given an account of 
the microscopic appearances of the various organs. I desire here to 
present a general summary of the more important pathological changes 
based upon the former observations and those made during the past 
summer. 
Notwithstanding what has been said to the contrary, phagocytosis 
goes on very actively in the blood, as seen in a fresh slide. The 
leucocytes are seen to be contracted into small spheres on first exam- 
ining the fresh drop of blood, but after about five minutes they begin 
to wander about and engulf whatever is foreign to the normal blood. 
These few minutes of inactivity are probably due to the shock of mak- 
ing the preparation. Both the eosinophiles and the rubinophiles (p. 
113) show themselves to be very voracious. In the hardened tissues, 
however, these cells, which are readily recognized by their oxyphilic 
granulations, are very seldom seen to contain any pigment. On the 
other hand the cells most actively phagocytic there are principally the 
endothelial and connective-tissue cells. The deposition of pigment, 
* Ann. de Vlnst. Pasteur, iv (1890), Parasitologic comparee, 1889. 
f Virchow’s Archiv, cxx and cxxi. 
J Arch. d. znol. cxper., 1894. 132 
On the Haematozoan Infections of Birds 
together with the remains of infected corpuscles, organisms, etc., 
forms the main pathological change in the organs, and in order to 
make this change plain I shall begin by describing an organ in which 
it is most simple. 
In the kidney, as in all the other organs, the capillaries and blood- 
vessels generally show a great number of infected corpuscles and some 
organisms extruded from the corpuscle. The epithelium of the tub- 
ules is in general fairly well preserved, although there are numerous 
instances of a hyaline degeneration of the cells. The glomeruli show 
nothing except the organisms within their capillaries. It is in the 
connective-tissue skeleton of the kidney with its contained capillaries 
that we see the main results of the infection. Many of the endothe- 
lial cells of the capillaries are much swollen and contain masses of pig- 
ment, yellow as well as malarial. Besides these there are cells be- 
longing to the connective-tissue framework, which have become store- 
houses of pigment—large cells with large round or oval vesicular 
nucleus, which have become so loaded with pigment, etc., as to be 
very conspicuous in the section. Ho epithelial cells have been seen 
invaded. 
In the intestine the connective-tissue cells of the stroma are phago- 
cytic and sometimes contain considerable masses of pigment. Similar 
cells occur also in the muscular wall imbedded among the muscle 
fibres, the pigmentation being deepest in the subperitoneal portion. 
The endothelial cells of the vessels in this tissue are also pigmented. 
The epithelial cells of the mucosa never show foreign contents. 
In the hone-marrow we have, besides fat cells and blood-vessels, cells 
large and small, which are generally spherical, with round nucleus 
and containing basophilic granulations, and other rounded cells and 
nuclei of various sizes with homogeneous protoplasm, all supported by 
a loose skeleton of connective tissue, made up of irregular, sometimes 
branching cells with pale ovoid nucleus. Of all these varieties of 
cells only the last are seen to be pigmented. Other large round cells 
do occasionally occur in the bone-marrow, however, which correspond 
closely to the red-corpuscle-carrying cells of the human spleen; these 
often contain several red corpuscles, some of which are infected. W. G. MacCallum 
133 
In the lung, hrain, and pancreas, although the capillaries contain 
many organisms, hardly any pigment deposit can be seen. 
The thyroid and adrenal, however, show a very considerable pig- 
mentation exactly corresponding in nature with that described for the 
kidney, the pigment being deposited in the endothelial and connec- 
tive-tissue cells of the interglandnlar tissue, the secreting cells escap- 
ing. The adrenal, however, differs in that red-corpuscle-carrying cells 
occur in its small vessels together with large free pigmented cells with 
hyaline protoplasm and vesicular nucleus. These resemble precisely 
the macrophages in the spleen, to be described presently. In the 
tissue adjoining the thyroid gland there are large spaces lined by 
epithelioid cells, many of which contain pigment masses, or even 
several infected corpuscles. Lying free in these spaces are many 
large red-corpuscle-carrying cells together with numerous red corpus- 
cles, leucocytes and cells desquamated from the walls, surrounded by a 
fine network apparently of coagulated fibrin. The nature of these 
spaces I do not know’ more exactly. 
In the pectoral muscle in one case there was a greyish opaque spot 
which on section showed a mass of necrotic material lying in the 
muscle and surrounded by richly cellular tissue, which was quite 
deeply pigmented. The neighboring muscle fibres were much frag- 
mented, with a proliferation of nuclei reminding one of that seen in 
the muscle in cases of trichiniasis. The tissue about the necrotic 
material had some of the characters of granulation tissue and was quite 
vascular, the elongated cells with large vesicular nucleus being the 
pigmented ones. Scattered about in this tissue were numerous giant 
cells with necrotic centre and many nuclei, such as are seen in miliary 
tubercles. Some of these were very large and without definite boun- 
daries. The large mass of necrotic material was closely bordered by 
groups of clustered nuclei, suggesting that it had arisen from the coales- 
cence of many giant cells. Through it there was scattered a good deal 
of malarial pigment. Whether all this diseased tissue in the muscle 
was due to the action of the hsematozoon is doubtful; it seems to me 
much more probable that the deposit of malarial pigment throughout it 
was entirely secondary to its formation by some other process. 134 
On the Haematozoan Infections of Birds 
In the liver we have often a very extensive deposit of pigment. 
The liver cells themselves are never phagocytic, hut the endothelial 
cells of the capillaries are often greatly swollen by their load of pig- 
ment and debris. In the blood-vessels, especially the branches of the 
portal vein, we find lying free the large macrophages, such as were 
seen to occur in the adrenal. These sometimes are so large as to con- 
tain masses of pigment equalling in size three or four liver cells. There 
are other phagocytic cells with large irregular nucleus which seem to 
lie between the liver cells and the endothelium and, although at first 
sight they have somewhat the appearance of liver cells, I am inclined 
to think them analogous to Emptier’s cells. 
It is in the spleen that these processes reach their acme. This organ 
is almost always greatly swollen and blackened, the deposit of pigment 
being so disposed as to show a black network on section. The vascular 
pulp of the spleen is arranged in bands forming a network in whose 
meshes lie the lymphoid elements. The pigment deposit is confined to 
these vascular bands beginning at the margins, where they are sharply 
marked off from the lymphoid tissue, and gradually involving most of 
their width. The bands appear to be made up of a spongy reticulum 
of endothelial cells, between which the blood flows. These cells are 
more closely arranged at the boundaries of the lymphoid tissue, where 
they become conspicuous early in the infection by their pigmentary 
contents. In more intense infections a great majority of the fixed 
cells making up the pulp become loaded with pigment, and thus give 
rise to the black network mentioned above. It seems probable that 
such loaded cells may be washed into the blood stream and constitute 
the so-called macrophages. These have been mentioned as occurring 
in the blood of the liver and adrenal, and they are also seen in num- 
bers in the veins of the spleen. They are cells varying greatly in size 
but generally of a somewhat rounded outline and with one or some- 
times two vesicular nuclei; their protoplasm is generally very clear 
and is seen to contain a great deal of foreign material—yellow masses 
of pigment as well as the balls, irregular masses, and granules of 
malarial pigment, broken-down blood corpuscles and disintegrated 
nuclei, together with shrunken parasites. The last sometimes occur W. G. MacCallum 
135 
in great numbers and form the only contents of the cell. In the 
spleen as elsewhere the endothelial cells of the vessel walls are often 
seen to be loaded with pigment. Red-corpuscle-carrying cells are not 
frequently seen. 
The pigment found in all these cells is not exclusively that formed 
by the parasitic organisms, as has been mentioned. A large part of. it 
is the iron-holding compound, or mixture of compounds, grouped 
under the name hsemosiderin, which are formed from the haemoglobin 
set free on the rupture of the infected corpuscles. 
We have, then, as the result of the haematozoan infections the pro- 
duction of one form of pigment by the parasites from the haemoglobin, 
and of another form by the tissues of the host from the haemoglobin 
set free into the blood. These solid pigments are stored up in the var- 
ious organs, but more particularly in the spleen and liver, in cells 
belonging exclusively to the connective-tissue group which also engulf 
the infected corpuscles, broken remains of corpuscles and shrunken 
dead parasites. The anatomical changes, therefore, differ very slightly 
from those seen in the human being in malarial infections, so well 
described by Bignami * and by Barker, f the greatest difference per- 
haps lying in the less important part played by leucocytes in the case 
of the bird. 
Finally, I wish to express my indebtedness to Dr. Thayer, of the 
Johns Hopkins Hospital, for his many kindnesses to me while engaged 
in this work, which was undertaken at his suggestion. 
ADDENDUM. 
Since the preparation of this article for the press I have examined 
the blood of a woman suffering from an infection with the eestivo- 
autumnal type of organism, in which a great number of crescents were 
to be seen. These in a freshly made slide of blood, with very few ex- 
ceptions, retained their crescentic shape for only a few minutes. They 
soon drew themselves up, thus straightening out the curve of the cres- 
cent while shortening themselves into the well-known ovoid form. 
* Bignami, Bull. d. r. Accad. med. di Roma, xix (1892-3). 
f Barker, Johns Hopkins Hospital Reports, v (1895). 136 
On the Haematozoan Infections of Birds 
After the lapse of 10 to 12 minutes most of them were quite round and 
extra-corpuscular, the “ hib ” lying beside them as a delicate circle or 
“ shadow ” of the red corpuscle. 
After 20 to 25 minutes certain ones of these spherical forms became 
flagellated; others, and especially those in which the pigment formed 
a definite ring and was not diffused throughout the organism, remained 
quiet and did not become flagellated. In a field where an example of 
each form could be watched, the flagella broke from the flagellated 
form and struggled about among the corpuscles, finally approaching 
the quiet spherical form; one of them entered, agitating the pigment 
greatly, sometimes spinning the ring about. The rest were refused 
admission, but swarmed about, beating their heads against the wall of 
the organism. This occurred after 35 to 45 minutes. 
After the entrance of the flagellum the organism again became quiet 
and rather swollen, but although in the two instances in which this 
process was traced the fertilized form was watched for a long time, no- 
form analogous to the “ yermiculus ” was seen. 
This process has also been observed once by Drs. Warfield and Pan- 
coast of the Johns Hopkins Hospital in another case of infection with 
the aestivo-autumnal parasite. It is evidently for the human being 
what was foreshadowed by the organisms of the bird. 
DESCRIPTION OF PLATE XII. 
All of the figures are of the Halteridium form of the parasite. 
Fig". 1.-—Adult granular, or female form. 
Fig. 2.—Adult hyaline, or male form. 
Fig. 3.—Adult female preparing for extrusion from the corpuscle. 
Fig. 4.—Adult male preparing for extrusion from the corpuscle. 
Fig. 5.—Adult female extruded and lying- beside the nucleus of the cor- 
puscle. 
Fig. 6.—Flagellate form. 
Fig. 7.—Process of fertilization. 
Fig. 8.—First stage in formation of motile form. 
Fig. 9.—Fully developed motile form or vermiculus. 
Fig. 10.—Fully developed motile form in process of disintegration. THE JOURNAL OF EXPERIMENTAL MEDICINE. VOL. 111. 
PLATE XII 
1 
2 
3 
4 
7 
5 
6 
10 
8 
9 
9