294 CONTAGIOUvS PLEURO-PNEUMONIA 



Pols and Nolen, in 1886, at Amsterdam, found round mi- 

 crococci always present in the exuded matter of the lungs. 

 These micrococci were about 0.9// in diameter and occurred 

 either isolated or in chains up to six in number. In the un- 

 stained preparation, the cocci were surrounded by a distinct 

 envelope which could be stained only with great difficulty 

 and which was absent from cultivated micrococci. 



Arloing believed that he had found the exciting cause of 

 the disease in various bacilli, especially in one in which he 

 C2i\\s pneumo-bacilhis liqtiefaciens bovis, which forms short, non- 

 motile rods. Arloing believes that his experiments prove that 

 the pneumo-bacillus is the cause of pleuro-pneumonia. 



In 1898, Nocard and Roux succeeded in obtaining a very 

 feeble growth of an exceedingly minute organism in bouillon 

 containing cow or rabbit serum in proportion of one part serum 

 to 25 parts bouillon, when cultivated in collodion sacs within 

 the abdominal cavity of rabbits. With these cultures the 

 disease was produced in cattle. 



§ 222. Symptoms. The symptoms are such as would 

 be expected with inflammation of the lungs and pleurae, but 

 they vary considerably according to the course which the 

 disease runs. If the attack is an acute one, as is frequently 

 seen in hot weather, the symptoms appear suddenly. The 

 breathing becomes rapid and difficult, the animal grunts or 

 moans with each expiration, the shoulders stand out from the 

 chest, the head is extended on the neck, the back is arched, 

 the temperature ranges from 104 to 107° F., the milk secretion 

 is suspended, loss of appetite, rumination is stopped, the 

 animal may bloat and later be affected with a severe diarrhoea. 

 Such cases are generally fatal in from seven to twenty days. 



Very often the attack comes on slowly and the symptoms 

 are more obscure. In the mildest cases there is a cough for a 

 week or two but no appreciable loss of appetite or elevation 

 of temperature. The lungs are but slightly affected and 

 recovery soon follows vSuch animals may disseminate the 

 virus for a long time without being suspected and for that 

 reason are the most dangerous of all. 



