180 



ACTIVE IMMUNIZATION 



few (e. g., less than 30 per 0.01 c.c.) and the absence of all suspicious 

 organisms, including the tetanus bacillus (the latter point is tested 

 by injecting a mouse with 0.01 c.c.), the lymph is placed in capillary 

 tubes, which are sealed at the ends, and is then ready for use. As 

 the activity of the vaccine diminishes in the course of time, each 

 preparation bears on its label the date, after which it should no 

 longer be employed. 



Fia. 12 



Vaccine vesicle upon the seventh day; areola just beginning. (Taken from Welch and Schamberg.) 



The Process of Vaccination. The field of vaccination, which is 

 preferably the upper portion of the upper arm, is first cleansed 

 with soap and water, and then with alcohol or ether. With a suit- 

 able instrument, which must be previously sterilized, two or three 

 parallel scratches are then made, about J cm. in length and 3 cm. 

 apart. A stout needle answers all purposes, and can be sterilized 

 by flaming the point and then cooling it in alcohol. If desired, a 

 new needle can be used for each case. Care should be taken that 

 the scratch extends to, but not through the papillary layer; actual 

 bleeding is to be avoided. The needle can either be charged with 

 the lymph from the start, and the scratches made with the vaccine 

 point, or a drop of the material is placed upon the scarified area and 

 subsequently rubbed into the little grooves with the body of the 

 needle. The removal of the lymph from the tubes is accomplished 



