304 THE DISEASES AND DISORDEES OP THE OX. 



and occurred only with comparative rarity. "It was matter of 

 popular tradition ; but was left for Jenner to demonstrate, that 

 persons who had thus been accidentally vaccinated enjoyed 

 immunity subsequently from small pox." (K. C. Seaton.) In 

 the year 1813 a report was published by the Imperial Institution 

 of France, which stated that 2,671,662 subjects had been 

 properly vaccinated in France, and that only seven of these had 

 afterwards taken the sraall-pox. In Prussia the number of 

 "persons who died from small-pox was reduced from 40,000 

 annually to 3,000. 



Although it is not yet settled beyond doubt, there seems to be 



Fig. 37. — Mickococci in the fresh Lymph of Human Small-pox. 

 1. Singly. 2. In dumb-bell-like pairs. 3. In short chains (after Klein)^ 



Fig. 38. — Lymphatic Vessel from the Skin of a Pock in the 

 CASE OF Sheep -pox. 



The vessel is seen to be filled with micrococci. 



every reason to believe that variola depends upon the presence of 

 a special and very minute micrococcus. Cohn found that the 

 lymph of vaccinia and that of variola contains numerous micro- 

 cocci. That the lymphatic vessels of the skin near the pocks 

 are full of micrococci, has been shown by Weigert in the ease of 

 small-pox of man, and by Klein in the case of sheep-pox. The 

 passage of these micrococci through the epidermis at the point 

 of vaccination in the calf has been traced by Pohl-Pincus. 

 When cultivated on the warm stage, and subjected to examina- 

 tion by the microscope, the micrococci are seen to form very 

 long chains and colonies. Still, as Dr. Klein points out, similar 

 micrococci occur in the fluid contents of vesicles in the skin 



