47 MICROBIOLOGY OF SPECIAL INDUSTRIES. 



the most important: smallpox vaccine, blackleg vaccine, rabies vaccine 

 (Pasteur treatment) and perhaps Pasteur's anthrax vaccine. The 

 simultaneous method, or injection of hyperimmune serum together with 

 the specific virus is used in vaccinating against hog cholera, cattle 

 plague (Rinderpest), anthrax and foot-and-mouth disease. Asiatic 

 cholera, bubonic plague, typhoid fever and tuberculosis are treated, 

 practically and experimentally, by various methods of vaccination. 



SMALLPOX VACCINE. The first experiments relative to vaccination 

 against smallpox date back to 1796. Prior to that time, the only specific 

 preventive method used in warding off this disease depended upon the 

 inoculation of healthy individuals with smallpox virus from a mild 

 case of the disease. The present method of vaccination consists of the 

 use of cowpox virus as the protective material. It has not been conclus- 

 ively determined that cowpox in cattle and smallpox in man possess 

 intimately related causative factors, but notwithstanding this unsolved 

 point, abundant evidence proves the efficacy of cowpox virus as a specific 

 prophylactic against smallpox in man. 



In the practical preparation of smallpox vaccine, the virus or "seed" 

 is first secured by removing the exudate from the vesicles which appear 

 on infected heifers. Most laboratories which engage in this work use 

 a stock mixture of cowpox virus which originated from spontaneous cases 

 of cowpox, and which is known to produce active smallpox vaccine. 



Great care is exercised in the selection and preparation of animals 

 used in making the vaccine. Calves or yearlings, and heifers are most fre- 

 quently used in this work, older cattle being employed in a few European 

 laboratories. When first purchased these animals are placed in a deten- 

 tion stable where they are inspected by a qualified veterinarian and care- 

 fully tested for tuberculosis. If, after several weeks' quarantine, they are 

 passed as healthy in every way, they are admitted to the vaccine laboratory 

 after their bodies have been scrubbed with soap and water and a weak 

 antiseptic solution. 



The operating room and propagating ward should be constructed 

 with a view to thorough cleanliness. Concrete floors, enameled walls 

 and ceilings and simple, sanitary apparatus should characterize the 

 appointments. Floors, walls, ceilings and all equipment of these rooms 

 should be carefully cleansed with disinfectant solutions at frequent 

 intervals. 



After the heifers are prepared for the work, they are inoculated with 



