INCUBATION PERIOD OF CHOLERA 161 



are young shoats which weigh from 50 to 100 pounds, and so are 

 just the right age and size to very quickly take the disease. 



Second, the amount of virus which enters the body of each 

 pig is quite large, and is much more than the animal would get into 

 its body under ordinary conditions in regular feed lots, even if 

 cholera were present in the herd, unless they were fed with the 

 dead bodies of animals which had died from cholera. 



This dose of virus does not seem to make as much of a difference, 

 however, as one might think. It has been found at the Ames serum 

 plant that an average dose of cholera virus will make the animal 

 sick just about as quick as will a much larger dose. 



The rapid appearance of cholera in these pigs at Ames is also 

 partly accounted for by the method used for getting the virus into 

 the body. Instead of feeding the germs to the animals with the 

 food, a syringe and long needle are used, and the pure hog-cholera 

 blood, containing millions of hog-cholera germs, is injected deep 

 in the muscles of the ham. In this way every one of the germs is 

 absorbed into the system, and they have a chance to work much 

 more rapidly than they would were they just given to the animals, 

 with the food. 



Another example of how quick hogs may be taken sick with 

 cholera when they get a large enough amount of the virus is shown 

 by the following case : A certain farmer in southern Minnesota had 

 left the farm, and with his wife moved to town. The oldest son 

 remained on the home place and ran the farm on a grain-rent 

 basis. At the home in the city the farmer had quite a large amount 

 of empty space, and so he fenced off a small pen in which he 

 placed two young barrow hogs. These two animals were fed with 

 the slop from the kitchen, and also with slop and refuse from the 

 kitchens of two or three of the neighbors, it being more convenient 

 to give it to the hogs than to hire a man to haul it away. It was 

 the intention to fatten these two barrows, and later on kill them for 

 winter meat supply. 



Along with other refuse which they received from the kitchens 

 was a considerable amount of pork trimmings, such as bacon rinds, 

 bones from pork chops, and other scraps of meat such as ordinarily 

 come from kitchens. Late in the summer one of the animals got 

 sick and in a few hours was dead. 



