I9i i.] The "Long Lactic Bacteria/' 311 



Rubinsky furnished an important contribution to the 

 subject in a report of his studies of koumiss.* In his 

 exhaustive examination of this fermented milk, he found that 

 milk containing extract of yeast was a very suitable medium 

 for such long lactic bacteria as exist in koumiss. 



The present writer, being specially interested in dairy 

 bacteriology, and doing bacteriological work in Dr. Lohnis's 

 laboratory in Leipzig, took advantage of the opportunities 

 offered him to investigate, as far as the time at his disposal 

 permitted, the distribution of these long lactic forms — lacto- 

 bacilli — to find out, if possible, whether their main sphere 

 of activity was confined to the above mentioned fermented 

 milks, or to confirm the results of Heinemann and Hefferen, 

 who found them to be very generally distributed. 



The medium employed was " yeast whey," a modification 

 of the yeast milk recommended by Rubinsky, and was pre- 

 pared as follows : 100 grams of yeast were added to 100 c.c. of 

 water, and this was heated in the steamer for from thirty to 

 sixty minutes, and filtered three times. The filtrate was 

 made up to 100 c.c. with water. To one litre of fresh separated 

 milk at 35 0 C. was added a little rennet extract. After 

 curdling this was stirred and heated to 70 0 C. and filtered. 

 To the filtrate or whey 1 per cent, of peptone, '5 per cent, of 

 common salt, and 10 per cent, of yeast extract were added. 

 The yeast whey was subsequently sterilised in the steamer 

 in the usual manner. The yeast whey so prepared was 

 found to be a better medium for the purpose than Rubinsky's 

 yeast milk. Being transparent it admitted of direct micro- 

 scopic examination of the different cultures at different periods 

 of incubation, and of direct observation of the relative growth 

 of lactobacilli in the cultures. 



Sterile tubes of this medium were inoculated with the 

 substances to be examined and incubated at 38 0 C. for several 

 days, or until bacterial growth was distinctly apparent. 

 Other tubes of yeast whey were inoculated from the first 

 cultures and incubated in a similar manner. When micro- 

 scopic examination had proved the long forms to be present 

 in considerable numbers, plate cultures were made with whey 

 agar and chalk. The lactobacilli were in this way isolated with 

 comparatively little difficulty. 



* Cenlralblatt fur Bakter., Bd. 28, 19 10. 



