BACTERIA IN SMALLPOX. 503 



always present, e.g., staphylococcus aureus and staphylococcus 

 cereus flavus, and many of the ordinary skin saprophytes 

 also are often present, but no organism has ever been 

 isolated which on transference to animals has been shown 

 to have any specific relationship to the disease. A bacillus, 

 however, discovered independently by Klein and Copeman, 

 and at present sub ju dice ^ may afford better results. Klein 

 observed this organism in lymph taken from a vaccine 

 pustule in a calf on the fifth and sixth days, in human 

 vaccine lymph on the eighth day, and in lymph from a 

 smallpox pustule on the fourth day. To demonstrate the 

 bacilli, cover-glass films are dried and placed for five 

 minutes in acetic acid (i in 2), washed in distilled water, 

 dried, and placed in alcoholic gentian-violet for from twenty- 

 four to forty-eight hours, after which they are washed in 

 water and mounted. Copeman and Kent also found the 

 bacilli in sections of vaccine pustules stained by Loffler's 

 methylene-blue, or by Gram's method. The organisms are 

 .4 to .8 fj. in length, and one-third to a half of this in 

 thickness. They are generally thinner and stain better at 

 the ends than at the middle. They occur in groups of 

 from three to ten in both the lymph and the tissues. In 

 the centre of their protoplasm there is often a clear globule, 

 which is looked on as a spore. They have hitherto 

 resisted the ordinary isolation methods, a fact which is 

 rather in favour of their non-saprophytic nature. By in- 

 oculating fresh eggs with the crusts of smallpox pustules 

 Copeman has, however, obtained a growth of a bacillus 

 resembling that found by him in the tissues. Though 

 subcultures on ordinary media have been obtained, the 

 pathogenic effects of these have not yet been fully investi- 

 gated, and thus the identity of this bacillus with that seen 

 in the tissues is not yet proved. The facts that the latter 

 is one hitherto not recognised microscopically, that it 

 exists in the pustules, the contents of which are probably 

 the means by which the disease naturally spreads, that it 

 resists artificial cultivation, that the possession by it of 

 spores explains some of the characteristics of vaccine lymph 



