ZOOLOGY AND BOTANY, MICROSOOPY, ETO. 573 



varying from 34-463 per cubic centimeter of snow-water. (2) That 

 their number does not decrease from exposure of snow to low tempera- 

 tures (— 16^ C.) for several days. (3) That the three following species 

 of microbes are constantly met with in great numbers : — (a) a large 

 diplococcus comi^osed of ovoid cocci, endowed with energetic motion, 

 and characterized by its rapidly liquefying gelatin. In test-tube 

 cultures greenish colonies form on the third day along the needle track, 

 and assume the shape of a funnel-like sac, with a whitish flocculent 

 deposit ; while by the fifth the whole medium becomes liquefied, and the 

 precipitate sinks to the bottom. On agar, a pale greyish streak is 

 formed at the site of inoculation ; on potato, a fairly thick white film. 

 (b) Small-sized cocci, often arranged two and two, energetically mobile, 

 and slowly growing on gelatin without liquefying the medium, the 

 growth proceeding slowly along the track of the needle in the shape 

 of a narrow strip consisting of non-coalescing points of a yellow colour, 

 while on the surface the colony is seen as a greyish-white circular 

 slightly prominent patch, with somewhat fringed edges. On agar the 

 coccus forms a white streak with sinuous edges ; on potato a grey film 

 with a brownish tint, (c) Very large cocci, liquefying gelatin as late as 

 three weeks after inoculation, and growing along the needle track in the 

 form of a sharply defined streak of a pink colour, with a slightly elevated 

 pink circular patch or cap on the surface. On agar the microbe forms a 

 freely spreading white film with a rosy tint ; on potato a thick tallow- 

 like pink coat, with sharply defined fringed contours. (4) That the 

 first two species are also met with commonly m the water of the river 

 Dnieper, while the pink coccus seems to occur only in snow. (5) That, 

 generally speaking, the microbes which liquefy gelatin are met with in 

 greater variety and in far greater numbers in falling or recently fallen 

 snow than in snow which has been on the ground for some time. This, 

 in fact, very often contains such bacteria as do not liquefy gelatin. 

 (6) That the bacteria of snow originate partly in aqueous vapours which 

 are transformed into snow, partly and chiefly in the air — that is, they 

 are carried away by the snow-flakes in their passage through the 

 atmosphere. 



1889. 2 II 



