188 Experiments on Variola and Vaccinia. [June 15, 



The chief difference noted between the effects resulting from the 

 local inoculation of these two diseases, in the monkey, is that in the 

 case of variola there is more or less of a crust from the first ; that 

 vesic ulation is much less marked in variolation than in vaccination ; 

 that with variola about the ninth to the eleventh day a general 

 eruption may appear which in some instances covers the whole sur- 

 face of the body ; and that the final scab at the site of inoculation is 

 not so elevated in the variolated as in the vaccinated animal. 



In both cases there is a rise of body temperature, which is more 

 marked and longer sustained in variola than in vaccinia. After 

 variolation it was noticed in several instances that the monkey 

 suffered from diarrhoea, that its eyes were suffused, and that it was 

 not as active as ususal. A peculiar odour was also noticed, quite 

 distinct from the well-known smell of "monkey." 



In no instance had the disease a fatal termination. 



It was next determined to make trial as to the protection against 

 small-pox afforded in the monkey by previous vaccination, and the 

 protection against vaccination afforded by variolation. And I went 

 on to compare the effect produced by the use of human and of calf 

 lymph respectively. 



As the result of numerous experiments, it would appear that the 

 mutually protective power of lymph obtained from these three different 

 sources when inoculated on the monkey is practically identical in all 

 respects. 



Experiments have also been carried out on the bacteriology of 

 vaccine lymph, with the view especially of discovering what means of 

 storage are best adapted for securing sustained purity of the lymph 

 and the unimpaired manifestation for indefinite periods of the 

 action peculiar and essential to its use. 



I have previously shown* that there are three species of micro- 

 organisms, one or other, or all, of which is almost universally to be 

 found in every specimen of vaccine lymph examined. These are 

 (1) Staphylococcus albus, (2) 8. pyogenes aureus, (3) S. cereus flavus ; 

 of which the first is frequently to be found in the upper layers of 

 healthy skin. Numerous other bacteria occur from time to time, 

 among which the Staphylococcus pyogenes deserves special mention. 



These " extraneous " organisms flourish in the various nutrient 

 media employed for cultivating purposes, and also in vaccine lymph 

 itself when removed from the body, causing, by their exuberant 

 growth, the opacity which sometimes occurs in old lymph stored in 

 capillary tubes. It appeared, therefore, not unlikely that in this 

 way the growth of the specific organism, if such exists, might be 

 superseded. 



Obviously, therefore, it was necessary to devise, if possible, some 

 * ' Transactions of International Congress of Hygiene,' 1891. 



