362 REPORT -OF-THE-COMMISSIONER OF-AGRICULTURE. + 
+ 
SUPPLEMENTAL REPORT. 
Sir: Since the 15th of November, the day on which J forwarded to you my full re- 
port, I have devoted my time principally to a solution of some of those questions 
which had not been fully answered, and have succeeded in ascertaining some addi- 
tienal facts of practical importance. In addition to this the correctness of my conelu- 
sions as to the nature of the infectious principle, and the manner in which swine- 
plague is communicated, has been confirmed by further observations. The vitality of 
the infectious principle has been tested by experiment; several herds of diseased swine 
and places where the disease had been prevailing, and where healthy pigs had been 
introduced a few weeks after the occurrence of the last case of swine-piague, have 
been yisited, and a few more post-mortem examinations have been made. In the fol- 
lowing, which may be cgnsidered as a supplement to my report of the 15th of Novem- 
ber, I have the honor of submitting to you, very respectfully, the results of my inves- 
tigation. 
1. THE BACILLI SUIS. 
These are found invariably, either in one form or another, in all fluids—such as blood, 
urine, mucus, fluid exudations, &c.—in all morbidly affected tissues, and in the ex- 
crements of the diseased animals, and constitute, beyond a doubt, the infectious prin- 
ciple, or produce the morbid process if transmitted, directly or indirectly, from a 
diseased animal to a healthy one. These bacilli undergo several changes, and require 
a certain length of time tor further propagation; consequently, if introduced into 
an animal organism, some time—a period of incubation; or a stage of colonization— 
must pass before morbid symptoms can make their appearance. Three stages of de- 
velopment (a germ or micrococcus stage, a bacillus or rod-bacterium stage, and a germ- 
producing stage) can be discerned. 
The micrococci, globular bacteria, or bacillus-germs, as I prefer to call them, are 
found in immense nunibers in the fluids, but especially in the blood and in the exuda- 
tions of the diseased animals. If the temperature is not too low, and if sufficient oxy- 
gen is present, they soon develop or grow lengthwise, by a kind of budding process— 
a globular bacterium, or bacillus-germ, constantly observed under the microscope, 
budded, and grew to double its length in exactly two hours in a temperature of 70° 
F. (see drawing)—and change gradually to rod-bacteria, or bacilli. Some of the latter, 
finally, after a day or two, if cireumstances are favorable, commence to grow again in 
length, until they appear, magnified 850 diameters, to be from one to six inches long. 
At the same time, however, they become very brittle, and break into two or more 
pieces. Where a break or separation is to take place, at first a knee or angle is 
formed, and then a complete break or separation is efiected by a swinging motion of 
both ends, which move to and fro, and alternately open and close, or stretch and bend 
the knee or angle. After the division has become perfect, which takes only a minute 
or two, both ends, thus separated, move apart in ditierent directions. These long bae- 
teria, it seems, are pregnant with new germs; their external envelop disappears or is 
dissolved, and then the very numerous bacillus-germs become free. In this way a 
propagation is eifected. 
Some of the bacilli or rod-bacteria move very rapidly, while others are apparently 
motionless. The causes of this motion I have not been ablé to ascertain with cer- 
tainty, but have observed repeatedly that no motion takes place if the temperature of 
the fluid or substance which contains the bacteria‘is a low one, and that under the mi- 
eroscope the motion increases and becomes more lively if the rays of light, thrown 
upon the slide by the mirror, are sufficiently concentrated to increase the temperature 
of the object. So it seems that a certain degree of warmth is required; at any rate I 
never saw any bacilli moving in a fluid or substance immediately after it had been 
standing in a cold room. 
There is, however, also another change taking place, caused probably by certain 
conditions which I have not been able to ascertain. It is as follows: The globular 
bacteria or bacillus germs commence to bud or grow in length, but on a sudden their 
development, it seems, ceases, and partially-developed bacilli and simple and budding 
germs congregate to colonies, agelutinate to each other, and form larger or smaller irreg- 
ularly-shaped and (apparently) viscous clusters. Such clusters are found very often in 
the blood and in other fluids, and invariably in the exudations in the lungs; and in 
the lymphatic gland in pulmonal exudation, and in blood serum, this formation can 
be observed under the microscope if the object remains unchanged for some time, say 
for an hour or two. In the ulcerous tumors on the intestinal mucous membrane the 
clusters are comparatively few, but the fully-developed bacilli, many of which move 
very lively, are always exceedingly numerous. The tumors or morbid growths in the 
intestines seem to afford the most favorable conditions for the growth and develop- 
ment of the bacilli and their germs. That this must be the case is also suggested by 
the presence of such immense numbers of bacilli and bacillus-germs in the excrements, 
