SECRETARY'S REPORT. 11 



The sick cows above mentioned were very sick, and exhibited 

 unquestionable evidence of pleuro-pneumonia. They were kept 

 entirely by themselves, and not allowed to approach the place 

 where the experiments were to be made. 



The Experimental Herd now consisted of seven animals, as 

 follows : — 



Tioo sick coivs ; one from Waltham, and one from Lexington. 



Tioo coivs from Waltham, which had made a part of a herd 

 in which pleuro-pneumonia existed. 



One coio from Maine, four years old. 



One heifer from Maine, about two years old. 



One cow, (a new milch cow.) which had been owned by me 

 two years. 



As it was found impracticable to obtain any land upon which 

 the experiments could be conducted, I selected my own grounds, 

 in Cambridge. Here a shed was built, twenty-four feet long by 

 twelve feet wide, open to the south, and closed upon the other 

 three sides. The cattle were secured with their heads towards 

 the open side. They were thus protected from sun and rain, 

 and enjoyed a free ventilation. Around the shed a fence was 

 built, to prevent the possibility of contact with other animals. 



May 25. — The experiments were commenced by placing a 

 healthy cow between the two sick ones. She was fed very 

 sparingly, to make her get her food from the two neighbors, by 

 which she would be exposed to their breath as much as possible, 

 and made to swallow any saliva which might be dropped upon 

 the hay. 



Each animal was exposed in this manner twenty-four hours, 

 some of them more. After all had been exposed, one of the 

 sick cows was killed, and the existence of pleuro-pneumonia 

 fully confirmed by examination after death. The amount of 

 disease was large ; both lungs were diseased ; their substance 

 and the pleura investing them. The disease was pronounced, 

 by those present, pleuro-pneumonia, of the same character as 

 that existing in Waltham and Lexington, and believed to be 

 contagious pleuro-pneumonia. 



The other sick cow was with calf, and was preserved for con- 

 tinued observation. The evidence of the existence of pleuro- 

 pneumonia in this animal was believed by those present to be 

 complete. 



