SYPHILIS 541 



But prevention is better than cure. So far as medicine is 

 concerned, the opening of the twentieth century will be recorded 

 in history probably as the beginning of the era of disease-pre- 

 vention. It was Edward Jenner who pointed out the path a 

 hundred years ago. He found that the inoculation of cow-pox 

 into human beings modified and prevented small-pox ; and to- 

 day small-pox does not exist in civilised communities. This is 

 advance indeed, and the beginning of the present century has 

 given us the application of his teaching — malaria, yellow fever, 

 tuberculosis, Malta fever, dengue, are being prevented wholesale, 

 and prevention is replacing the old retail method of individual 

 cures. We are learning to regard disease as an armed enemy 

 standing on the threshold of an unarmed homestead ; we must 

 find a means of shutting the door in his face rather than try to 

 attack him when inside. It was with this object in view that in 

 July 191 1 Mr. McFadden instituted researches at the Lister 

 Institute of Preventive Medicine into the causation and preven- 

 tion of certain of the zymotic diseases ; he suggested those 

 which produce the greatest death-rate — measles and scarlet 

 fever. His object was to find out a means of preventing them. 

 These researches have resulted in advancing our knowledge, 

 not only of scarlet fever and measles, but also of syphilis. 



A start was made with the examination of the blood of cases 

 of acute scarlet fever and measles. For this the newly invented 

 "jelly method" of staining living cells was employed. The 

 jelly method is a considerable improvement on the older tech- 

 niques by which dead cells distorted by alcohol and other 

 fixatives were examined ; it is better than the dark-ground 

 illumination, which only shows the shadows of living things. It 

 consists in placing living cells on a soft jelly where they can be 

 watched under the microscope ; they are spread out gently, 

 remain alive for hours, and their component parts are made to 

 stain slowly. Thus their action can be observed and the pre- 

 sence of parasites detected better than by any other known 

 method. The jelly method showed peculiar inclusions within 

 the large mononuclear cells of the blood in all cases of scarlet 

 fever and measles during the acute febrile stages of those 

 diseases. 



But, as it was found difficult to ascertain the exact nature of 

 these intracellular bodies (the same difficulty which Siegel had 

 to face) which stain in a peculiar manner by the jelly method, a 



