NATURE OF VACCINATION 609 



through 46 transfers on the cornea of the rabbit, and, further, no 

 similar appearances have been found in other skin lesions. 

 Prowazek examined material fixed in a hot mixture of two- 

 thirds saturated perchloride of mercury and one-third 98 per 

 cent, alcohol, washed in 40 per cent, iodine alcohol and stained 

 in Grenacher's heematoxylin, and found bodies in the epithelial 

 cells 1 to 4 ^ in size, sharply contoured and having ragged 

 edges as if made up of massed chromosomes. These were often 

 broader at one end than at the other, and appearances have 

 been seen which suggest longitudinal division. Prowazek has 

 also seen these " lymph-bodies," as he has called them, in the 

 lymph, and he inclines to the idea that they may be protozoa. 

 Bonhoff and also Carini have described spirochsetes as occurring 

 in variolous lesions, but this has not been confirmed. Volpino 

 states that in the epithelial cells in corneal infection in rabbits, 

 minute motile bodies can be discerned which do not occur in 

 other corneal inflammations. Future investigations must show 

 what significance is to be attached to these various observations. 



The causal organism of smallpox is probably very small, as 

 there is little doubt that it will pass through the coarser porcelain 

 filters. 



The Nature of Vaccination. From the facts known regarding 

 vaccination we are justified in supposing that the principle 

 underlying the efficacy of this prophylactic is the establishment 

 of an active immunity against the causal organism, which is 

 sufficiently lasting to protect the vaccinated individual for a 

 considerable time. Although the virus of smallpox is unknown, 

 several attempts have been made by indirect methods to 

 establish the existence of reactions similar to those occurring 

 in other immunisations. Thus, in cases of human smallpox 

 and in animals intravenously injected with the vaccine lymph, it 

 is stated that the serum when mixed with vaccine lymph acquires 

 the property of deviating complement, and evidence has also been 

 obtained by Prowazek that the serum of monkeys infected 

 subcutaneously contains substances of the nature of anti-bodies, 

 for, when it is mixed with the lymph, the mixture is not 

 capable of originating a vaccine pustule in children. Phenomena 

 of hypersensitiveness on re vaccination have also been described. 



Considerable attention has been devoted to the study of the 

 effects of corneal and cutaneous infection in the rabbit and 

 monkey. Here it has been found that the infection of one 

 cornea protects that eye against re-inoculation but not the other 

 eye. Further, it is stated that while cutaneous vaccination 

 causes the general skin surface after about ten days to become 



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