[Reprinted from The Philadelphia Medical Journal, November 19, 1898J 
EXPERIMENTAL STUDIES ON THE ORIGIN OF THE 
CHARCOT-LEYDEN CRYSTALS, WITH AN AC- 
COUNT OP THEIR CHEMISTRY, OCCURRENCE AND 
DIAGNOSTIC IMPORTANCE. 
THOMAS R. BROWN, M.D., 
of Baltimore, Md. 
The part played by the Charcot-Leyden crystals upon 
the medical stage has been a most varied one. Though 
at first regarded as mere pathologic curiosities, rarely 
seen and of no especial significance, later observations, 
by showing their tendency to occur frequently or even 
constantly in certain diseases and morbid conditions, 
have given them a much more important position and, 
in some, cases, some diagnostic significance. In the 
present communication, I shall give the results of a 
series of experiments bearing upon the origin of these 
crystals, together with a brief but complete account of 
their occurrence, properties and importance. 
The first definite notice taken of the crystals under con- 
sideration dates from their discovery, in 1853, by Char- 
cot and Robin in the spleen of a patient who had died 
of leukemia. Probably they had been seen before; in 
fact, Zenker, in 1876, wl>en interest in this subject had 
been greatly increased by the work of Neumann and 
Leyden, resurrected from the “ darkness of his portfolio ” 
a drawing and a description of crystals undoubtedly 
the same as those of Charcot, and from the same source, 
bearing the date 1851. Following the work of Charcot 
and Robin, there appeared many articles describing the 
finding of these crystals in the most diverse situations. 
Besides a rapidly growing list of their occurrence in the blood, marrow, spleen and other tissues in leukemia, 
and their demonstration by Neumann in 1869 in the 
normal bone-marrow in smaller quantities, there ap- 
peared from time to time observations of their presence 
in the sputum in various diseases of the lungs and 
bronchi, culminating in the work of Leyden, and his 
demonstration of their almost constant occurrence in 
the sputum in bronchial asthma, while Leichtenstern, 
Bizzozero, and others have found them in many dis- 
eases of the intestines caused by different varieties of 
the entozoa. More recently Lewy has shown that they 
occur in the majority of nasal polyps and papillomata. 
In addition to these conditions in which they are seen 
very frequently, observations of their occurrence in the 
most unexpected situations have been made; in 1854 
by Forster in a mucoid tumor of the eye, and in the 
thickened mucous membrane of a dilated biliary 
duct; in 1862 by Wagner in a thrombus in the portal 
vein of a woman who had died of puerperal sepsis ; by 
Eichhorst in a purulent pleural exudate, and by Lewy 
in a carcinoma of the cervix ; while Salkowski states 
that the crystals obtained by Zahn in artificial thrombi 
jn frogs, and by Brondgeest from frozen frogs’ blood, are 
identical with those under consideration. 
Practically the same description of the crystals is 
given by all observers. They are long drawn-out double 
pyramids, with flat sides and sharp angles, colorless, 
exceedingly brittle, of varying size and most resistant 
to putrefying processes. As to the crystallographic sys- 
tem to which they belong, they have been variously 
regarded as quadratic octohedra, rhombic plates and 
monoclinic forms, though the work of Theodore Cohn 
seems to show beyond doubt that they are double hexa- 
gonal pyramids. The crystals are insoluble in cold 
water, alcohol, ether, xylol, chloroform and creosote ; 
soluble in almost all acids and alkalies, and they show 3 
a marked affinity for the eosin and acid-fuchsin stains. 
Besides their common designation of Charcot-Leyden 
crystals, they have appeared under the names of Robin, 
Vulpian, Neumann and Zenker. 
After the discovery of the crystals by Charcot and 
Robin in leukemia, there followed a long series of 
reports of their occurrence in this affection, by Vulpian, 
White, Hosier, Riegel, Neumann, Zenker, etc., etc. Ac- 
cording to all these observers, the crystals are not found 
preformed, but they begin to appear after the blood or 
tissues have stood for a short time. Zenker and Neu- 
mann stated that the most striking feature in their 
blood-preparations was the close relationship that 
seemed to exist between the crystals and the white 
blood-cells. This was, of course, before the days of the 
Ehrlich stain and the differentiation thereby of the 
white blood-cells into different classes, but later work 
has shown that the cells for which the crystals evidence 
such an affinity are the eosinophiles, the cells with 
oc -granulation of Ehrlich. Neumann, in his later observ- 
ations on this subject, in 1889, has shown that it is only 
in that form of leukemia in which the bone-marrow is 
affected, i. e., the spleno-myelogenous form, that the 
crystals are found, and he regards it as probable that 
the bone-marrow cells (many of which are eosinophiles) 
contain the chemic constituents necessary for the 
crystal-formation, although Zenker and Westphal think 
the spleen also plays some part in this process. 
Coincidently with the many observations of the crys- 
tals in leukemia, numerous articles appeared from time 
to time showing that the crystals are not peculiar to 
this disease, but also found under other conditions. 
Again, to Charcot do we owe our first knowledge on this 
subject, he, in 1856, noting their presence in a case of 
dry catarrh with emphysema. Bizzozero and Friedreich 
observed them in the sputum in bronchial catarrh, and 4 
Forster, Zenker and Harting in bronchitis. This was 
the status of affairs when, in 1872, a great impetus was 
given to the whole subject by Leyden’s report of the 
finding of great numbers of the crystals in the sputum 
in bronchial asthma, he finding them in all parts of the 
sputum, but especially in the little greenish-yellow 
plugs, made up of mucus and round cells with large 
refractive granules (demonstrated later by Lewy, Seifert, 
and others, to be eosinophiles). From their constant 
presence in this disease, Leyden advanced the theory 
that these “ spitzenformige Bosewichter ” might be the 
cause of the asthmatic attack through mechanical or 
chemic irritation of the bronchial mucous membrane, 
causing bronchial spasm, either directly or reflexly. 
The observations of Leyden stimulated much work in 
this direction, and in all respects his observations were 
substantiated. Lewy showed in 26, Ungar in 30 cases, 
the constant presence of the crystals, the former noting 
their presence just before, during, and for from two to 
three days after the attack ; the latter calling especial 
attention to the close relationship existing between the 
eosinophiles and the crystals. Fink has recently shown 
that over 80% of the cells in the sputum in bronchial 
asthma are eosinophiles, while he, Seifert, Gollasch, 
Gabritschewsky, Muller, and others have shown a 
marked increase of these cells in the blood during the 
asthmatic paroxysm. 
Although Curshmann regards his “ spirals ” as the 
cause of the dyspnea by blocking up the bronchioles, 
and Lewy and Pel regard all these substances—crystals, 
spirals and eosinophiles—as by-products of a primary 
cause, an exudative bronchopneumonia; nevertheless 
Leyden, in 1891, again brought forward his original 
theory, following the work of Lazarus, showing the reflex 
nature of the asthmatic attack. 
Although the crystals have been described in a few 5 
cases of acute and chronic bronchitis, and by Nanny n 
and Lewy in four cases of pulmonary tuberculosis, 
nevertheless their presence in these conditions is so 
very occasional, that their appearance in the sputum 
may be regarded as almost pathognomonic of bronchial 
asthma. 
Voltolini showed as early as 1871, a clinical relation- 
ship between nasal polyps and bronchial asthma, being 
substantiated by Lewy, Vierordt, and others; while 
Scheinmann has shown that by the removal of nasal 
polyps, asthmatic attacks have been stopped. Lewy, 
turning his attention to this new source of the crystals, 
obtained them in 32 of 47 cases of nasal polyps; in 17 
of 29 in those who had not bronchial asthma, and in 15 
of 18 in those affected with this disease, the crystals 
not being preformed, but appearing on standing. Sei- 
fert in his cases reports the presence of large numbers 
of eosinophiles as well. 
As regards the presence of the crystals in the feces, 
their first observation was made by Bizzozero in a severe 
anemia, associated with the presence of the dochmius 
duodenalis in the intestines. It is to Perroncito and to 
Leichtenstern, however, that we owe most of our 
knowledge upon this subject, the former demonstrating 
their presence in the feces in association with the anchy- 
lostomum and the anguillula; the latter in almost all 
of his 272 cases of anchylostomiasis, in all cases in 
which the anguillula was found, and in many instances 
of intestinal disease due to other entozoa—the oxyuris 
vermicularis, tricocephalus, taenia saginata, taenia soli- 
um, and ascaris lumbricoides, and he regarded the crys- 
tals as absolutely indicative of the presence of entozoa, 
continuing the treatment until they are no longer found 
in the stools. He has shown that the crystals are found 
both before and after death only in those portions of 
the intestines occupied by the worms, and he thinks 6 
more careful examination would have demonstrated the 
presence of entozoa in all cases in which the crystals have 
been found in the feces, notably in some cases of ty- 
phoid fever reported by Biiumler and Nothnagel. Many 
eosinophiles are often seen in the feces in all these 
cases, while a marked eosinophilia has been described 
in the blood of patients suffering with anchylostomiasis 
by Zappert and others. 
Beside the foregoing findings of Leichtenstern and 
Perroncito, a few observations of rarer associations 
between crystals and parasites have been noted—by 
Leichtenstern in the sputum in 3 cases of echinococcous 
disease of the lungs; by Grawitz in a purulent pleural 
exudate in all probability entozoic in origin; by Israel 
in a small cyst formed by the pentastomum denticu- 
latum in the liver and by Yamagiwa in the sputum in 
the lung-distome disease of Japan. 
Up to 20 years ago, the chemistry of the Charcot- 
Leyden crystals was an unsolved problem, each observer 
advancing suggestions, no one offering chemic facts. 
Charcot thought they were proteid in nature, Robin 
that they were magnesium phosphate, Harting, cal- 
cium phosphate from morphologic resemblances, Kiihne 
that they were related to vitellin, Hoppe-Seyler to the 
aleuron crystals of plants, while Zenker and Friedreich 
regarded them as tyrosin, and Salkowski and Leyden 
as a crystallized, mucin-like body. This was the chaotic 
state of affairs that greeted Schreiner,'when he took up 
the subject in 1878. As, unfortunately, crystals from 
the sputum or from leukemic blood were not available 
in sufficient quantity, he worked with the crystals 
obtained by Bottcher in 1866, on drying human semen, 
as well as upon the surface of old pathologic specimens 
preserved in alcohol, and from egg-albumin. These 
crystals showed the same micro-chemic reactions as 
the Charcot-Leyden crystals, were of almost, though 7 
not quite, the same form, and in all respects the resem- 
blance was so striking that the two forms were regarded 
as identical. By exceedingly brilliant work, Schreiner 
showed that these crystals were the phosphoric-acid 
salt of a base, C 2HSN, which he called spermin. 
Thus, the matter of the chemistry of the Charcot-Ley- 
den crystals was regarded as settled, until the whole sub- 
ject was reopened at the tenth international medical con- 
gress. A few years before this congress, Brown-S6quard 
and Tarchanov had obtained a powerful principle from 
the testicles of animals, the famous elixir, and to this 
were ascribed the most wonderful tonic and strengthen- 
ing properties, marvelous cures being reported as having 
been effected by it in tabes dorsalis, malaria, and all 
conditions of asthenia and anemia. It was from this 
substance that Pohl isolated crystals identical with 
those of Bottcher, and it was his belief that these were 
the active principle of the elixir that stimulated further 
chemic research in this direction. Sobering prepared 
synthetically a substance identical with Schreiner’s 
base, which he called piperazin, or piperazidin; Laden- 
burg and Abel showed that the base C2H,;N was in 
reality ethylenamin 
,ch2 
NH( | 
XCH, 
while Hoffmann, Majert and Schmidt considered that it 
should have the double formula C 4H10N2, and that it 
was diethylendiamin 
,CH2—H,Cv 
nh/ >nh 
X)H2 H2C/ 
The Brown-Sequard elixir has gone the way of most 
of the royal roads to health, but Dr. Pohl still clings 
to the spermin-crystals as powerful stimulants, regard- 8 
ing their tonic action as largely due to the important 
role they play in intraorganic oxidation. He has ob- 
tained the crystals in small quantities from most of 
the organs, although most abundantly from the pros- 
tatic secretion, and he regards the spermin and Charcot- 
Leyden crystals as identical, claiming to have converted 
one form of crystal into the other, and assigning 
to each the formula C 5H14N2 or some polymer. 
Nevertheless, the slight difference in crystallographic 
form, as insisted upon by Guttmann and Ffirbringer, 
and recently demonstrated by Theodor Cohn, leaves us 
in some doubt regarding the question, and although 
the two forms of crystals are regarded by the majority 
of observers as identical or at least extremely closely 
related, further work will be necessary to settle the 
matter definitely. 
Thus, it will be seen that the Charcot-Leyden crystals 
are found in the most diverse situations, in the sputum 
in bronchial asthma, in the feces in diseases due to 
intestinal parasites, in nasal polyps, in the blood and 
organs is leukemia and in normal bone-marrow; and 
the sole thread that binds together these diverse ap- 
pearances is the constant association that exists be- 
tween the crystals and the eosinophilic cells. The 
preponderance of eosinophiles in the sputum and their 
increase in the blood in bronchial asthma; the pres- 
ence of crystals only in those forms of leukemia that 
show an increase of the eosinophiles in the blood ; the 
finding of the crystals in the normal bone-marrow, 
which is considered to be one of the seats of origin of 
the eosinophiles; the increase of eosinophiles in the 
nasal secretion in some cases of polyp; the association 
of crystals and eosinophiles in the feces in intestinal 
diseases due to entozoa; the repeatedly made observa- 
tions of the close arrangement of crystals and cells, 
and their identity in affinity towards the acid stains— 9 
all point to a close relationship between them. That 
something beside the presence of the cells, however, is 
necessary for the crystal-formation is shown by a series 
of experiments carried on by me in the summer of 
1897. The source of the eosinophiles in these experi- 
ments was the blood of a patient suffering with trichi- 
nosis. In this disease, as I have reported elsewhere, 
there is a marked increase in the eosinophilic cells in 
the blood, reaching in the case studied at that time 
68.2% of all the white blood-cells, with a leukocytosis 
of from 20,000 to 30,000, thus furnishing an abun- 
dance of these cells. On nine occasions blood was 
withdrawn from the patient, some placed in sterilized, 
some in unsterilized vessels, some kept in the thermo- 
stat at body-temperature, some kept at room-tempera- 
ture, i.e., it was tested under practically all conditions. 
The blood under each of these conditions was ex- 
amined carefully—very frequently at first, daily after- 
ward for a period of several weeks, but under no 
circumstances in any of the preparations were the 
Charcot-Leyden crystals found; thus demonstrating 
that they are not direct crystallization-products of the 
eosinophiles. With these results, the experiments 
carried on by Muller entirely agree, he obtaining his 
eosinophilic cells from the contents of pemphigus- 
vesicles, where they are found in abundance. What, 
then, is this relationship, it is impossible to say; 
whether the crystals are formed in the lymph-spaces of 
the bronchial mucous membranes, as suggested by 
Leyden and Weiss; whether the eosinophiles are drawn 
from the blood by a positive chemiotaxis, which Muller 
thinks the crystals possess toward them; whether cells 
and crystals are formed in situ, as Gollasch and Seifert 
think probable; or whether the whole process, forma- 
tion of cells and crystals, is but a secretion-neurosis, as 
believed by Neusser—all these questions must for the 10 
present remain unanswered. But one thing can settle 
the matter definitely, and that is the clearing up of the 
chemistry of the cell-granulations, and it is from this 
side, and this side alone, that we can look for further 
progress in the matter. Unfortunately, even our modern 
chemic methods are not capable of the refinements 
necessary to such a study, and the Ehrlich stains, 
although helping us wonderfully in cell-differentiation, 
yield us practically no information regarding the 
chemistry of the cell-granulation. 
Perhaps in the near future, the chemistry of these 
microscopic particles will be a possibility; but until 
then we shall be compelled to say of this, the most 
interesting question connected with the Charcot-Leyden 
crystals, as for the same reason wTe must say of many 
greater and weightier medical problems, “ non liquet.”