SMALLPOX. 327 



sequent variolation. After a large series of further suc- 

 cessful vaccinations Jenner, in 1798, published his famous 

 communication, in which he announced the established fact 

 of the protective influence of cowpox-lymph against small- 

 pox. Since then, vaccination against smallpox has been 

 gradually adopted in all civilized countries ; in Germany it 

 has been made obligatory through a law passed in 1874. 

 In those countries in which the general practice of vaccina- 

 tion against smallpox is regulated by law, variola, which 

 formerly was responsible for a large proportion of the mor- 

 tality, has almost completely disappeared. Devastating 

 epidemics now occur only in uncivilized countries. Vacci- 

 nation against smallpox is practised in Germany in the first 

 and twelfth years ; it consists in the cutaneous introduction 

 of the contents of the pocks of young calves in a fresh 

 state or rubbed up with glycerin (animal vaccination). The 

 lymph obtained from the vesicles of inoculated persons has 

 the same effect (humanized lymph). Of late, however, 

 animal lymph is almost universally preferred, as the danger 

 of simultaneous transmission of other disease-products 

 (syphilis, etc.) can not with certainty be excluded in the 

 use of humanized lymph. Animal lymph is obtained in 

 Germany by systematic vaccination of calves in institutes 

 under State supervision. 



In accordance with existing knowledge, it can be defi- 

 nitely accepted that cowpox is identical with variola in 

 human beings, and that vaccinia is only a form of variola 

 mitigated by passage through the body of the cow. Fischer, 

 of Karlsruhe, succeeded in grafting the virus of variola 

 on the body of the calf by collecting and mixing together 

 the liquid and the contents obtained by cureting from vario- 

 lous pustules in human beings in their various phases, from 

 development to suppuration. The mixture was then rubbed 

 into the largest possible surfaces (crucial incisions and 

 scarification). Fischer was .able in this way to develop in 

 the calf directly with the virus of variola typical pustules 

 whose contents, subsequently upon reconveyance to human 

 beings, from the third generation, proved to be vaccine. 

 Vaccination against smallpox thus readily adapts itself to 

 current views regarding immunity, inasmuch as it represents 

 a protection against disease induced through preventive 

 inoculation of an attenuated though similar virus. 



As to the nature of the virus of variola, numerous 



