126 



Dr. S. Monckton Copeman. 



[Nov. 13, 



It would appear also that, as in the human subject, young animals 

 are more susceptible to small-pox than are adults, since it was in 

 those instances in which monkeys probably not more than a year 

 old were variolated that the most successful results were obtained. 

 In one instance, however, in which the monkey was believed to be 

 not more than a few months old, the extremely fine downy hair, after 

 shaving, grew again so rapidly as to render somewhat difficult the 

 photographing of the effect produced by the operation. 



Mode of Operation and Collection. 



In the earlier experiments inoculation of the monkey with human 

 small-pox emulsion was carried out by rubbing it well into scarified 

 patches or linear incisions of the skin of the upper arm or of the inside 

 of the thigh, after previous shaving and cleansing of the skin. Subse- 

 quently, however, in accordance with the suggestion of Dr. de Haan, 

 a shaved area on the back of the animal was utilised for inoculation. 

 In this situation the results of the operation were found to be equally 

 good, and there is less liability of damage to the vesicles from the 

 monkey scratching itself. 



The eruption having arrived at maturity, after the lapse of a period 

 extending from five to eight days from inoculation, the altered epi- 

 thelium was removed either with a small Yolkmann's spoon or by 

 scraping with a scalpel, after cleansing the inoculation area, between 

 the blades of pressure forceps. The resulting epithelial pulp was then 

 rubbed up in a small glass mortar, with the gradual addition of about 

 six times its weight of normal saline solution, containing, when it was 

 desired to preserve and purify the emulsion, 50 per cent, of glycerine. 



Experience has shown that in monkeys a year or more old, which 

 have been inoculated, the vesicular stage of the eruption is at its height, 

 as was formerly observed in the human subject, by the eighth day ; but 

 in younger animals the process tends to be hastened, and in some of 

 the later and most successful cases, the eruption was completely 

 vesicular as early as the sixth day (120 hours). The particular breed of 

 monkey does not appear to exert any influence in this respect. 



Transference to the Calf and Human Subject. 



The methods employed for transference of the localised disease in the 

 monkey, after one or more passages through that animal, to the skin of 

 the calf need not be set out in detail, being similar to those ordinarily 

 used in the process of calf vaccination But it may here be stated that 

 at no stage of the investigation have these experimental calves been 

 brought into contact with, or even placed in the same room as, the 

 calves used in the current work of the Government Vaccine Establish- 



