616 THE STREPTOCOCCI OF ANIMALS 



Agar. o n a g ar slopes a thick spreading growth is formed which is at 

 first white and then somewhat yellowish. 



Potato. On potato growth is always poor. A greyish, scalloped film 

 forms which slowly acquires a yellowish tint. 



SECTION III. VACCINATION. 



Bridre vaccinated ewes by giving them two inoculations on each side of 

 the abdomen of 0*5 c.c. of a broth culture attenuated by keeping it in the 

 hot incubator (37 C.) for 3 or 4 months. A small abscess or slough often 

 formed at the site of inoculation ; the animals were immunized in about a 

 fortnight. 



Bridre has shown that the serum of hyper-immunized sheep has prophy- 

 lactic properties. 



