92 Immunity 



three days vesiculation, three days pustulation, and subse- 

 quent cicatrization with the formation of a punctate scar. 



An arm may be never so sore, may suppurate or even 

 become gangrenous, without vaccinia having occurred or 

 the desired benefit attained. 



The accidents of vaccination were formerly numerous and 

 sometimes disastrous because of the general inattention to 

 the quality of the materials used, the mode of inserting them, 

 the condition of the patient's skin, and the careless treat- 

 ment of the resulting lesions. When human virus was used, 

 the transmission of human diseases, such as syphilis and 

 erysipelas, occasionally took place ; now these are rare acci- 

 dents indeed. When no attention was paid to the quality of 

 the bovine virus, and no governmental inspection of labor- 

 atories required, the accidental contamination of the virus 

 occasioned a small number of accidental infections of the 

 patients' arms, but these evils are becoming less and less as 

 greater attention is given to the details of the process. 

 Some accidents and some few deaths there will probably 

 always be, just as there are occasional accidents and occa- 

 sional fatal results following all kinds of trivial injuries, 

 though care will eliminate them as the sources of accident 

 are better understood. 



3. Bacterination: Although the word vaccination is de- 

 rived from the Latin vacca, "a cow," and was first em- 

 ployed in connection with Jenner's method of introducing 

 virus modified by passage through a cow, it has now by cus- 

 tom become applicable to any kind of protective inoculation, 

 and the word bacterination is only introduced for the purpose 

 of indicating certain differences in the method. 



In 1 88 1 Pasteur,* in experimenting with Bacillus anthracis, 

 observed that if the organism were cultivated at unusually 

 high temperatures it lost the power of producing spores, and 

 diminished in virulence. He also found that when the organ- 

 isms had been so attenuated, they could not regain virulence 

 without artificial manipulation. It occurred to him that 

 such organisms, possessing feeble virulence, might be able 

 to confer immunity upon animals into which they were 

 inoculated, and continued to investigate the subject until he 

 found that by using three "vaccines" or modified cultures of 

 increasing virulence, it was possible to render animals immune 



* " Compte rendu de la Soc. de Biol de Paris," 1881, xcn, pp. 662- 

 665. 



