416 THE QUESTION OF IMMUNITY AND ANTITOXINS 



correctly termed) was practised in this country, until by Act of 

 Parliament in 1840 it was prohibited. There were different methods 

 of performing variolation,^ bat the most approved was similar to the 

 modern system of arm-to-arm vaccination, the arm being inoculated, 

 by a lancet in one or more places, with small-pox lymph instead of, 

 as now, with vaccine lymph. As a rule, only local results or a 

 mild attack of small-pox followed, which prevented an attack of 

 natural small-pox. But its disadvantage is apparent : it was in fact 

 inoculating small-pox, and it was a means of breeding small-pox, 

 for the inoculated cases were liable to create fresh centres of infection. 



In 1796, Edward Jenner, who was a country practitioner in 

 G-loucestershire, observed that those persons affected with cow-pox, 

 contracted in the discharge of their duty as milkers, did not contract 

 small-pox, even when placed in risk of infection. Hence he inferred 

 that inoculation of this mild and non-infectious disease would be 

 protective against small-pox, and would be preferable to the process 

 of variolation then so widely adopted in England. Jenner therefore 

 suggested the substitution of cow-pox lymph (vaccine) in place of 

 small-pox lymph, as used in ordinary variolation. 



It should not be forgotten that variolation was thus the first 

 work done in this country in producing artificial immunity, and 

 was followed by vaccination, which was only partly understood. 

 Even to-day there is probably much to learn respecting it. Vaccina- 

 tion may be defined as active immunisation hy means of a weakened 

 form of the specific virus causing the disease. The nature of the 

 specific virus of both small-pox and cow-pox awaits discovery. 

 Burdon Sanderson, Orookshank, Klein, Copeman, and others have 

 demonstrated bacteria in cow-pox or vaccine lymph, and in 1898 

 Copeman announced that he had isolated a specific bacillus and 

 grown it upon artificial media.* Numerous statements have been 

 made to the effect that a specific bacillus has been found in small-pox 

 also. But neither in small-pox nor cow-pox is the nature of the 

 contagium really known.f 



These facts, however, did not remove the suspicion which had 

 hitherto rested upon vaccine lymph as a vehicle for bacteria of other 

 diseases which by its inoculation might thus be contracted. A few 

 remarks are therefore called for at this juncture upon the work of 

 Copeman and Blaxall, in respect to what is known as glycerinated 

 calf lymph. Evidence has been forthcoming to substantiate in some 

 measure the distrust which many persons have from time to time 



* An exhaustive account of vaccine may be found in the Milroy lectures, delivered 

 in 1898 at the Royal CoUege of Physicians by S. Monckton Copeman, M.D., 'Brit. 

 Med. Jour., 1898, vol. i., pp. 1185, 1245, 1312 ; see also paper on the " Bacteriology 

 of Vaccinia and Variola," Brit. Med. Jour., 1902, vol. ii., pp. 52-67. 



t Crookshank, Bactenology and Infective Diseases ; Virchow, The Ituxley Lecture, 

 1898. 



