SMALLPOX AND COWPOX. 653 



Animals. The preferable animals are female calves, 

 from two to four months of age, in good condition and 

 free from any skin disease. These can be vaccinated 

 on the posterior abdomen and inside of the thighs easily 

 by placing them on an appropriate table. It is possible 

 that on account of the character of the available supply 

 older animals may be desirable, but the calves take 

 more typically and are more easily handled. When 

 an animal is too old to be thrown and held easily it 

 may be vaccinated on the rump, each side of the spine; 

 but the skin there is tougher, and the resulting virus, 

 though efficient, is not so easily emulsified. 



Vaccination. The calf should be cleaned thoroughly, 

 including the feet and the tail, and the hair should be 

 clipped from the end of the tail. The posterior abdo- 

 men and insides of the thighs are then shaved and the 

 skin beneath washed in succession with soap and water, 

 sterilized water and alcohol, and then dried with a 

 sterile towel. On this area there are then made about 

 one hundred scarifications, each from one-quarter to 

 one-half of an inch on a side. The scarification is 

 made most easily by cross-hatching with a six-bladed 

 instrument, the blades being about one-thirtieth of an 

 inch apart. The scarification is superficial, but brings 

 blood. An area as small as specified is less likely to 

 become infected than a larger one. The scarifications 

 should be separated from each other by an interval of 

 at least one-half to three-quarters of an inch. After 

 they have been made they should be dried with a sterile 

 towel or cotton and rubbed with the charged slips. One 

 to two slips, depending on the amount of virus each slip 

 contains, should be sufficient for vaccinating each ves- 

 icle. 



