THE EMPLOYMENT OF CENTRIFUGAL FORCE 
AS AN AID TO THE EXAMINATION 
OF SPUTUM. 
BY 
THOMAS G. ASHTON, M.D., 
CHIEF OF THE OUT-PATIENT MEDICAL DEPARTMENT IN THE JEFFERSON MEDICAL 
COLLEGE HOSPITAL AND DEMONSTRATOR OF CLINICAL MEDICINE 
IN THE JEFFERSON MEDICAL COLLEGE J 
AND 
A. H. STEWART, M.D., 
CLINICAL ASSISTANT IN THE OUT-PATIENT MEDICAL DEPARTMENT IN 
THE JEFFERSON MEDICAL COLLEGE HOSPITAL. 
FROM 
THE MEDICAL NEWS, 
October 6, 1894. [Reprinted from The Medical News, October 6, 1894,] 
THE EMPLOYMENT OF CENTRIFUGAL FORCE 
AS AN AID TO THE EXAMINATIO N OF 
SPUTUM. 
By THOMAS G. ASHTON, M.D., 
CHIEF OF THE OUT-PATIENT MEDICAL DEPARTMENT IN THE JEFFERSON 
MEDICAL COLLEGE HOSPITAL AND DEMONSTRATOR OF 
CLINICAL MEDICINE IN THE JEFFERSON 
MEDICAL COLLEGE J 
AND 
A. H. STEWART, M.D., 
CLINICAL ASSISTANT IN THE OUT-PATIENT MEDICAL DEPARTMENT IN 
THE JEFFERSON MEDICAL COLLEGE HOSPITAL. 
To facilitate the examination of sputum for tuber- 
cle bacilli, and to render more conclusive such 
examinations when but few bacilli exist in a given 
specimen of sputum, as well as to offer a substitute 
for the complicated methods now in vogue for the 
detection of fibers of elastic lung-tissue, are the 
objects of the present paper. When sputum con- 
tains tubercle bacilli in but scanty numbers it fre- 
quently happens that repeated examinations are 
necessary before their presence can be satisfactorily 
demonstrated ; and even then their existence at 
times fails of detection, as will presently be shown, 
when by the aid of the centrifuge that they exist in 
such sputum can be readily made clear. 
So also the application of centrifugal force, in the 
manner about to be described, to the detection of 
elastic fibers will be found a great improvement over 2 
the present methods. For this purpose at present 
the plan most generally adopted is that advocated 
by Fenwick, which consists in boiling the sputum 
in a dilute solution of caustic potash, then allowing 
it to settle for twenty-four hours, and examining 
the sediment for elastic fibers under the micro- 
scope. To those who are in the habit of employing 
this method it is not necessary to call attention 
either to its complications or to the uncertainty of 
its results, both of which render its employment 
practically useless in the ordinary routine of clini- 
cal work. Nor is the simpler method advocated by 
von Jaksch, of adding some potash solution directly 
to the sputum as it is placed upon the slide, with the 
object of dissolving the pus and allowing the elastic 
fibers to be seen, to be any more strongly recom- 
mended, as it is open to the chief objection that 
characterizes Fenwick's method, viz: its uncer- 
tainty, and the number of examinations usually 
necessary before, if at all, the elastic fibers can be 
found. 
The observations about to be described were 
made from sputa taken from patients presenting 
themselves at the out-patient medical department of 
the Jefferson Medical College Hospital; and be- 
cause in the present paper it is desired to describe 
the effect of centrifugation only as it may apply to 
the tubercle bacillus and elastic fibers of lung tissue, 
none other than tuberculous sputum is included. 
This is done, too, notwithstanding that sputa 
belonging to other diseases of the lungs have been 
similarly treated, as, for example, the sputum from 
cases of bronchial asthma, in which we have found 3 
that Charcot-Leyden crystals and the spirals of 
Curschmann can also be very readily demon- 
strated. 
The mode of procedure is as follows : The in- 
strument utilized to produce the required centrifugal 
force is a machine made by F. F. Metzger, of Phila- 
delphia, under the direction of Judson Daland, as a 
modification of the hematokrit of Blitz-Hedin, with 
the difference that the caliber of the glass tube in 
which the precipitation is to take place is two-and- 
one-half millimeters in diameter, instead of one- 
half millimeter, as is the case with the hematokrit. 
In both instruments the length of the tube is the 
same, about fifty millimeters. Inasmuch as the 
greater the number of revolutions of the precipitat- 
ing tube we are able to produce in a given time so 
much less time will be required in the manipulations, 
thereby simplifying the procedure, the machine 
made by Metzger is advocated, as no instrument yet 
brought to the attention of the writers has been 
found to approach it in speed. Though as yet 
untried, the force derived from a small electric 
motor might be utilized with advantage for the pur- 
pose of furnishing the necessary power for the opera- 
tion of the centrifuge. 
The preparation of the sputum before placing it 
in the precipitating tube is extremely simple. A 
small quantity is placed in a porcelain dish, and 
actively stirred for a few moments with a glass rod. 
Under this treatment the sputum soon becomes, 
without the addition of any diluting fluid, a thin 
liquid, free from lumps, and apparently of homo- 
geneous character. The precipitating tubes are 4 
then filled, the sputum being drawn into them by 
means of rubber tubing having attached to one end 
a small rubber bulb to produce the necessary suc- 
tion. We have used for this purpose an ordinary 
medicine-dropper with its attached bulb, inserting 
the nozzle end of the dropper into the end of the 
rubber tubing, the other end of which is applied 
over the end of the precipitating tube. This method 
has been adopted to render unnecessary suction by 
the mouth which, were there no other reasons why 
it should not be resorted to, might not be free from 
danger in the case of tuberculous sputum. For the 
purpose of elucidation a drawing of this simple ap- 
paratus is given, and so easy of application is this 
method that its use has been resorted to for the 
drawing up of the blood into the precipitating tube 
of the hematokrit, as it has been found that the 
column of blood is thus more susceptible of control 
than it is with mouth suction. 
Fig. i. 
Medicine dropper attached by rubber tubing to 
precipitating-tube. 
The two precipitating tubes filled with sputum 
thus prepared are now placed in the centrifuge, and 
rapidly revolved for at least two minutes. With a 
speed of ten thousand revolutions per minute, which 
is easily attained by the improved apparatus made by 
Metzger, two minutes is quite time enough to pro- 
duce complete precipitation of the more solid por- 5 
tions of the sputum, along with which, as shall 
presently be shown, go the objects of our search. 
Precipitation thus having been accomplished, to 
the unaided eye the sputum will be found to have 
separated into two layers; that at the distal or periph- 
eral end of the tube being yellowish or greenish 
in color; that at the proximal or central end appear- 
ing as a slightly turbid, almost transparent watery 
fluid, which by the microscope is found to contain 
no cellular elements whatsoever. In the peripheral 
end of the tube, however, the microscope reveals, 
closely packed together, but their integrity not in 
the least impaired, the various forms of epithelial 
cells and pus cells contained in the sputum. The 
more purulent is the character of the sputum, the 
greater the amount of desquamation of epithelium, 
of course the greater will be the depth in the pre- 
cipitating tube of the purely cellular portion of the 
sputum-an observation possibly not without its 
value. 
Undoubtedly the most important evidence that a 
destructive process is taking place in the pulmonary 
structure is to be found in the discovery of elastic 
fibers in the sputum. With obscure symptoms 
and signs pointing to a pulmonary tuberculosis, 
their significance is even greater than the presence 
of tubercle bacilli, unless in large numbers, as 
bacilli may be found in sputum when the lungs are 
in no wise diseased. The finding of elastic fibers is 
positively indicative of destruction, and the other 
destructive diseases of the lungs, such as bronchiec- 
tasis and pulmonary abscess, are not by their symp- 
tomatology likely to be confounded with tubercu- 6 
losis. Pulmonary gangrene is not here classed with 
diseases of the lungs characterized by destruction of 
the lung-tissue, and to be compared with tubercu- 
losis, because, as was first pointed out by Traube, 
the sputum expectorated in cases of pulmonary 
gangrene rarely contains elastic fibers, for the reason 
that they are probably completely destroyed within 
the gangrenous area. Therefore, the presence of 
elastic fibers in the sputum, with signs and symptoms 
pointing to pulmonary tuberculosis, even though 
these be obscure, and even though the presence 
of the tubercle bacillus may not be demonstrated, 
would clearly establish the diagnosis of pulmonary 
tuberculosis. Hence, that which will supplant the 
complicated and uncertain method of Fenwick, 
or the somewhat less complicated but none the less 
uncertain method of Von Jaksch for the detection of 
elastic fibers, cannot fail to be of great practical 
value when the importance of the subject is taken 
into consideration. 
From the large number of observations we have 
made, now amounting to many hundreds, it has 
been definitely demonstrated that elastic fibers are 
precipitated by centrifugal force in the largest num- 
bers to the very extremity of the peripheral end 
of the precipitating tube. The sputum occupying 
this portion of the tube, when rich in cellular ele- 
ments, is found to be quite thick in consistence, 
and is usually extruded as a mold of the interior 
of the tube. Without any dilution, or any means 
for the solution of the pus cells, a small portion of 
this sputum taken from the periphery of one of the 
tubes-the contents of the other tube being reserved 7 
for the examination for tubercle bacilli-is spread 
somewhat thinly upon a slide, the cover-glass being 
pressed down to effect its equable distribution. 
Examined in this way, if the sputum contain any 
tissue its presence cannot fail of discovery. Ex- 
amining the contents of the precipitating tube 
throughout its entire extent for elastic fibers, they 
are found to rapidly diminish in numbers as we pass 
from the periphery; and this is found to be the 
case even when the sputum contains lung-tissue in 
abundance, as was clearly demonstrated in one case 
especially, in which in the first slide were discovered 
ten separate collections or bundles of fibers, while 
in the second slide but three were found, and in the 
third but one, none being found beyond the third 
slide. The bundles of fibers were much larger in 
the first slide. In the thin, watery portion of the 
sputum, or that which remains after the precipita- 
tion of the cellular and other solid elements, elastic 
fibers are absent altogether. Elastic fibers examined 
by this method do not differ in appearance from 
those found after the methods usually practised for 
their detection, and the accompanying drawings 
of collective fields of sputum taken in succession, 
beginning at the peripheral end of the precipitating 
tube and proceeding toward the central end, pre- 
sent good illusrations both of the appearance of the 
cast-off lung-tissue and its relative frequency in the 
slides, as the examinations take place away from the 
periphery of the precipitating tube. 
It is the experience of everyone accustomed to 
examine sputum for the tubercle bacillus that in 
those cases in which the number of bacilli is very Elastic fibres. D objective, ZEISS, a. Slide prepared from extreme periphery of precipitating tube. b. Collective field from a 
slide taken 5 mm. from peripheral end of tube. c. Collective field from a slide taken 1 cm. from peripheral end of tube. 
Fig. 2. Tubercle bacilli. Homogen. immers. ZEISS, a. Slide prepared from extreme periphery of precipitating tube. b. Slide taken 
5 mm. from peripheral end of tube. c. Slide taken i cm. from peripheral end of tube. 
FIG. 3. 10 
small the result of the examination is often disap- 
pointing, and a number of such examinations have 
to be made before the presence of the bacilli can 
be demonstrated. Indeed, cases are not infre- 
quently met with in which bacilli are not found in 
the sputum even after repeated examinations, and yet 
such cases will have presented well-marked evidences 
of pulmonary tuberculosis. 
By centrifugal force, together with the pus cells 
and the various forms of epithelium, the tubercle 
bacilli are carried along. Thus it is that they are 
found in greatest abundance at the peripheral end of 
the precipitating tube. Centrifugal force does not 
separate them and assign them a place of their own, 
but they rather share the fate of the cellular ele- 
ments of the sputum, which therefore carry the 
bacilli along with them. Hence it is, that with the 
bacilli as with elastic fibers, as we pass from the 
peripheral toward the central end of the precipitat- 
ing tube they are found to rapidly diminish in 
numbers, until when the watery portion of the 
sputum is reached their presence fails of demon- 
stration. That this is the case and the extent to 
which it is so, the appended drawings of slides pre- 
pared and stained from different portions of the 
tube will clearly show. 
The value of centrifugal force as an adjunct to 
the examination of sputum for tubercle bacilli when 
they exist in only few numbers can scarcely be 
overestimated. Again and again have our obser- 
vations demonstrated to us the facility whereby in 
such cases the presence of bacilli can be discovered 
by the aid of centrifugation, and in cases, too, in 11 
which at the same time they were found only after 
much trouble and repeated examinations by the 
ordinary methods. This was especially noticed in 
a case in the wards of the Jefferson Medical College 
Hospital, which presented well-marked signs of 
advanced pulmonary tuberculosis, among them 
being the physical signs of a large cavity below the 
left apex anteriorly. In August, 1894, this case 
died, and the autopsy fully confirmed the diagnosis 
of pulmonary tuberculosis. The sputum of this 
case had been examined repeatedly by the ordinary 
methods, not only by ourselves but also by others 
expert in making sputum examinations, and at no 
time were bacilli found; and yet in this very case, 
by the aid of centrifugation bacilli were found in 
the sputum at the first examination, the number 
being very few. 
In the course of these observations we have tried 
various ways of previously diluting the sputum, and 
have also considered the advisability of endeavor- 
ing to secure the solution of the pus corpuscles, 
thinking that by these means the tubercle bacilli 
and the elastic fibers would be more closely col- 
lected together. 
We also subjected sputum to a series of examina- 
tions according to the method advised by Biedert, 
which, as described by Von Jaksch, consists of the 
following procedures : " Ten to twenty cubic centi- 
meters of the sputum are boiled in a watch-glass with 
a little dilute caustic soda; water is added, and the 
mixture again boiled until it is thinly fluid. It is then 
allowed to stand in a conical glass for two or three 
days, after which the sediment is added to a small 12 
quantity of egg-albumin, and examined for bacilli 
in the usual manner." Instead of allowing two or 
three days for sedimentation, the mixture was at 
once subjected to centrifugation, but the result was 
far from satisfactory. 
In this connection reference should also be made 
to the method recently described by Ilkewitsch 
( Centralblatt fur Bakteriologie und Parasitenkunde, 
Feb. 5, 1894, Bd. xv, Nos. 5, 6, p. 162), the pre- 
liminary procedures of which consist in mixing with 
a half cubic centimeter of sputum in a porcelain 
dish twenty cubic centimeters of distilled water. 
To this are then added eight to twenty drops of a 
30 per cent, solution of potassium hydroxid, and 
the mixture warmed until vaporization occurs, until 
which time it is constantly stirred. Under the in- 
fluence of the heat and the potassium hydroxid, 
complete solution of the sputum is supposed to take 
place, at which time a small amount of casein is 
added to the mixture and dissolved. The fluid is 
then poured into a test-tube and acetic acid added, 
drop by drop, until the first sign of coagulation of 
the albumin is observed. The liquid is then placed 
in the cylinder of the centrifuge and rotated until 
separation of its elements takes place. When the 
separation has occurred a small ball suspended by a 
thread is lowered into the cylinder upon the col- 
lected sediment, and the superimposed fluid allowed 
to flow out. The sediment is then treated accord- 
ing to the special method which it is the object of 
the paper of Ilkewitsch to set forth. 
In the course of our work upon the subject we 
found that dilution of the sputum as a preliminary 13 
measure to centrifugation is not only unnecessary, 
but interferes materially with the success of the ex- 
amination, as it lessens the actual amount of sputum 
precipitated and diminishes the number of bacilli 
and elastic fibers available for observation, as well 
as increases the difficulty of staining. It is further 
rendered unnecessary because the sputum, by the 
process of trituration as above described, is rendered 
sufficiently fluid for proper manipulation; indeed, 
such sputum, even though abundantly rich in cellu- 
lar elements, after centrifugation is found to be 
composed of more than one-half water. 
The same objections apply to the various methods 
resorted to for causing a solution of the sputum, 
and it seems to us that such methods as those ad- 
vised by Biedert and Ilkewitsch needlessly compli- 
cate what should be only a very simple process. 
The object of both of these methods is especially 
directed to the collecting together of bacilli, from 
sputum containing them in but scanty numbers, 
within a limited space. For accomplishing this pur- 
pose that method which is the simplest in its details, 
and which requires but a very few moments for its 
completion, provided that its object is effected 
with the same precision as by the more complicated 
means, is the method that will prove most practi- 
cable in the routine of clinical work. Furthermore, 
other things being equal, why should methods that 
are both complicated and time-consuming be fol- 
lowed when one presents itself in which both these 
objections are lacking ? That we are not over- 
estimating the value of the simple method just 
described, we think we have abundantly proved. 14 
In looking into the literature of the subject we 
find but few references to the adaptation of centri- 
fugal force to sputum examination, and the few 
obtained refer only to the precipitation of tubercle 
bacilli, and nowhere do we find recorded any ob- 
servations upon the effect of centrifugation upon 
elastic fibers. We therefore feel that the observa- 
tions made in the present paper, so far as they refer 
to this part of the subject at least, are original. 
In conclusion we would say that, as a result of 
the above investigations, in the centrifugal machine 
we possess a very important adjunct to the present 
methods in use for the examination of sputum. 
Nor in its adoption will clinical medicine be bur- 
dened with a new instrument, as the centrifuge has 
so many well-demonstrated uses that in any clinical 
laboratory its presence is indispensable. In the 
form of the hematokrit its value is now acknowl- 
edged, and as a means for procuring the sedimenta- 
tion of urine it possesses sufficient importance to 
warrant its possession were that the sole claim for 
its adoption; and, finally, that it is of practical 
value in the examination of sputum has been con- 
clusively proven in the clinical laboratory of the 
out-patient medical department of the Jefferson 
Hospital, where for the past six months the routine 
examinations of sputum have been conducted with 
its aid. The Medical News. 
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