13 



se subjects is 60 °/o> and in general as 

 much as 41 / o . 



In proportion as the animal population 

 grows denser, the facility of contagion 

 is greater for all species. Such condi- 

 tions of contagion reach their maximum 

 when, in spite of keeping the cattle at 

 grass, i.e. in the open fields and air, 

 they are specially employed in a way 

 which keeps them crowded together and 

 in continual contact. As for example j 

 in our rural cow-sheds situate in rich 

 pasture land, with 2 to 5 head per hec- 

 tarea, where the cattle is penned up once 

 or twice a day for milking, where the 

 calves are enclosed in yards so small 

 that they have no room to move freely, 

 the proportion of ihe attacked is consi- 

 derably greater. 



In this class of establishments the in- 

 fected animals whose excretions are full 

 of bacilli, become a constant and real 

 danger. 



One alone is sufficient in some cases 



