DISEASES OF SWINE AND OTHER ANIMALS. 53 



SUPPLEMENTAL EEPORT. 



Sir : Since the 15tli of November, the day on wMch I forwarded, to yon 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- 

 tional facts of practical importance. In addition to this the correctness of my conclu- 

 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 occiUTcnce of the last case of swine-plague, have 

 been visited, and a few more pont-vxortem examinations have been made. In the fol- 

 lowing, which may be considered as a supplement to my report of the IGth 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 hacilli undergo several changes, and require 

 a certain length of time for 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 numbers 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 hacilli. Some of the latter, 

 finally, after a day or two, if circumstances are favorable, conunence to grow again in 

 length, until they appear, magnified 8.50 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 j)lace, 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 ai^art in different directions. These long bao- 

 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 effected. 



Some of the iacilli or rod-bacteria move very rapidly, while others are apparently 

 motionless. The causes of this motion I have not been able 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- 

 croscope 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 hacilli 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, l)ut on a sudden their 

 development, it seems, ceases, and partially-developed hacUli and simple and budding 

 germs congregate to colonies, agglutinate to each other, and fonn 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 lymph.'.tic gland in pnhnonal exudation, and in blood serum, this formation can 

 be observed under the microscope if the object remains unchanged for some time, say 

 for an ho'ur or two. In the ulcerous tumors on the intestinal nmcous membrane the 

 clusters are comparatively few, but the fully-developed hadUi, many of which move 

 very lively, are always exceedingly munerous. The tumors or morbid growths in the 

 intestines seem to afford the most favorable conditions for the growth and develop- 

 ment of the hacUU and their germs. That this must bo the case is also suggested by 

 the presence of such immense numbers of bacilli and bacillus-germs in the excrements, 



