THE LUNG PLAGUE. 29 



CONTAGION AND INFECTION. 



Not only have theories in relation to the cause or combinations of causes which may 

 lead to the development of pleuropneumonia been unsatisfactory, but opportunities are con 

 stantly presenting themselves to test the fact that privations, overcrowding, impure food 

 and water, &c., singly or combined, may kill, but never induce the disease which presents 

 the characteristics of the one referred to in this report. 



The malady may be induced at will, by placing an animal suffering from it among 

 healthy ones, and by direct inoculation. These are the only methods by w r hich it is 

 propagated. 



Careful experiments have been instituted on this subject, and although it might be 

 easy to refer to very numerous observations, it may suffice at present to quote from a 

 French report, edited by Professor Bouley, and which was prepared by a committee of 

 distinguished agriculturists, medical and veterinary professors, at the request of the 

 minister of agriculture. 



FIRST SERIES OF EXPERIMENTS. 



The first series of experiments was conducted at Pomerage, in the well-known and 

 vast domain of Rambouillet. The whole is inclosed by walls, surrounded by woods, and 

 perfectly isolated. A stable was separated into two distinct compartments. In the first, 

 designated A, with a southwest exposure, was a single door leading out on a sufficiently 

 wide plot of ground, bounded by water where the cattle could be taken to drink. Every 

 precaution was taken to prevent the cattle in A from coming within reach of those in the 

 second stable, B. The latter was situated to the left of A, and completely separated by 

 a solid wall. 



Pleuropneumonia had never existed in the commune of Rambouillet. Messrs. 

 Renault, Delafond, and Jouet chose the cattle and subjected them to a close examination. 

 The herd consisted of three bulls and seventeen cows. These animals were distinguished 

 by names and numbers, and distributed in the two stables in relation to age, breed, and 

 sex, so as to secure an equable distribution. 



Three sick cows were sent to Rambouillet on the 14th of November, 1851 one from 

 the D6partement du Nord, the second from Mont Souris, and the third from Vaugirard. 

 Three more sick cows were sent on the 2d of December, 1851. Of these six sick animals, 

 three died and three recovered. One lived three days in stable A, a second five days and 

 a night in the same, and the third, in stable B, survived ten days and two nights. 



Of the three sick cows that recovered, one, admitted into stable A on the 10th of 

 November, presented symptoms of the malady up to the 20th of December, viz : for thirty- 

 four days. The second entered stable B on the 2d of December, and was sick for nine 

 teen days. The third, also admitted in the same stable, continued ill for twenty-eight days. 



/Stable A. On the 21st of November, 1851, viz: only six days after the introduction 

 into this stable of two sick cows, a peculiar cough was shown by two cows, (La Noire, 

 No. 16, and Norma, No. 2.) Their lungs appeared sound, and they continued to eat and 

 ruminate. 



The same symptom manifested itself successively, as follows : 



First, on Coquette, (No. 3,) on the 22d of November. 



