KEFIR. 157 
threads, individual joints of which are readily demonstrated by the use of fuchsin. He states that he 
observed threads from 10 to 40 long. Most of these were not straight but wavy and bent. They 
form commonly an interwoven, felt-like layer. The growth of Leptothrix threads due to unfavorable 
conditions usually precedes spore formation. In such threads there is a row of spores, while in the 
single vegetative cells which do not grow out into threads, there are always only two spores in a cell, 
one at each end (fig. 39). The spore formation begins with the appearance at each end of the cell 
of a small, bright dot, which gradually increases in size, becomes bounded by a sharp contour and 
is finally converted into a true spore. ‘These spores are always round and their diameter never 
exceeds the thickness of the cell. The figure borrowed by von Freudenreich represents not spores 
but germinating spores. ‘The shortest cell observed with two polar spores measured 34. Most of 
them were 6. long. The longest seen was 20n. He was never able to find any cross-wall separating 
the two spores, not even when he used Hartnack Imm. X. He, therefore, concludes that the two 
spores are certainly inclosed in one cell. He could not make out in the vegetative cells whether the 
_ spore formation was brought about by free cell-formation or by cell-division. On the contrary, in 
the Leptothrix threads he found a plain cell-division. The round free-lying spores reach a diameter 
of tu. The germinating spores swell up to a diameter of 1.64. He was able to observe the germination 
and has figured it, but it is not perfectly clear from his statements whether these germinating spores 
were those from the Leptothrix threads, or those from the motile organism or from other non-motile 
short rods or whether they really had anything to do with the organism concerned in the kefir sym- 
biosis. After considerable discussion of the views of earlier writers on the systematic position of 
the bacteria, he describes his organism, Dispora caucasica as follows: 
“Vegetative cells in the form of short cylindric rods, 3.24 to 8uX0.8u. In zoogloee condition 
the cells form white compact elastic clumps of considerable size (up to 5 cm.).* The motile vegetative 
cells have at one end a thin thread-like, wavy flagellum. ‘he spores are round. Lying in the cells 
they do not exceed the breadth of the 
latter. When they are free they are 93 
Iu in diameter. The round spores are 
always arranged two in a cell, one at eg . 24 
each end.” Hi % SS 
The kefir clumps do not appear to SS 3 D 1] B 
lose power of growth by drying. They ! es = Qj 
shrink considerably, become dirty p 
brown and stone hard, but are able 3, oO , a R 
again to resume their activity ‘when Sa 
thrown into milk, and are preserved RV, 
by the mountaineers in a dry condition 
for a long time. The author himself Fig. 39.* 
preserved them in an air dry place for 
two months, and after a few days, when thrown into milk these could not be distinguished from 
fresh clumps nor was there any perceptible difference in their power of fermentation. Under the 
microscope the dry clumps showed a considerable number of changes. Many of the yeast-cells 
were dead and those which remained alive were principally spherical. These dried ones contained 
no spores. ‘The Dispora when in spore condition is said not to be destroyed by boiling for an hour. 
The foregoing is the substance of Kern’s paper in the Bulletin de la Société Impériale des Natural- 
istes, Moscow, 1881. He sums up his conclusions as follows: 
(1) The little clumps, the ferment of the Kephir, afford an interesting example of a symbiotic 
life—commensualism (?)—of yeast-cells and bacteria. 
(2) The yeast-cells are to be considered as the ordinary beer-yeast, Saccharomyces cerevisiae 
Meyen. 
(3) The bacteria, in the vegetative condition scarcely to be distinguished from Bacillus subtilis 
Cohn, may, on the ground of very peculiar spore formation, be set off into a new genus, near the 
genus Bacillus—Dispora caucasica, nov. gen., nov. sp. 
(4) A distinct cell-membrane can be distinguished on the vegetative cells of the Dispora. 
(5) The motile cells of the Dispora have a thin, thread-like, wavy flagellum at one end. 
(6) Moreover, the little clumps, but especially the vegetative cells and the spores of the Dispora, 
are very resistant to unfavorable influences. 
This paper is followed by two tables of figures. From them I have borrowed the two 
figures 38 and 39. 
*Fic. 39.—Spore formation in Dispora caucasica, and also mature and germinating spores (25). After Kern. In 
his fig. 23 at p, p, are masses of protoplasm which he states he observed to break up into two spores. In his figure 
24 are a group of vegetative cells provided with a spore at each end and destitute of any cross-wall between them. In 
his fig. 23, one, two and three are said to be stages following each other in spore development. 
