EXPERIMENTS UPON THE LIVING ANIMAL. 93 



few days. Similarly, animals fed upon the nodules 

 of bovine tuberculosis become tubercular, and even 

 upon the flesh and milk of tuberculous animals 

 will occasionally set up tuberculosis. 



Cutaneous and Subcutaneous Inocula- 

 tion. Cutaneous inoculation may be carried out 

 by making a superficial wound, and inoculating 

 it with a sterilised platinum needle, charged 

 with the micro-organisms to be inoculated. An- 

 other simple method is to take a sterilised knife, 

 infect the point with the material to be inoculated, 

 and then make a minute wound or incision. In 

 either case a situation should be selected, such as 

 the root of the ear, which cannot be licked by 

 the animal after the operation. 



Subcutaneous inoculation is very simple and 

 effectual, and consequently the method most fre- 

 quently employed. The animal selected for 

 example, a guinea-pig is held by an assistant, 

 who covers it with a towel, leaving only the hinder 

 extremities exposed. By so doing, and gently 

 laying it upon its back, with its head low, a 

 guinea-pig passes apparently into a state of 

 hypnotism, and the trivial operation can be per- 

 formed with little or no movement on the part 

 of the animal. From a spot on the inner side 

 of the thigh the hair is cut close with a small 

 pair of scissors curved on the flat, and the skin 

 must be thoroughly purified with sublimate solu- 

 tion. A small fold of skin is then pinched up 



