210 ORGANIC FOODSTUFFS. 



experiments by the quantity of carbon dioxide liberated from 

 the cultures, and did not make any exact determinations on the 

 number of cells sown and gathered. This, it should be distinctly 

 observed, is a factor that does not affect the principle of the 

 question ; but in later researches it was impossible to forget, in 

 the investigation of the conditions of cell reproduction, the 

 quantity of the matter influenced, as well as the dimensions of 

 the influence. This requirement was first satisfied by AL. 

 Kossowicz (I.) in 1903. This worker, operating with pure 

 cultures of Sacch. ellipsoideus I. (Hansen) and the distillery yeast, 

 Race II. of the Berlin Experimental Station, found, for instance, 

 that 200 cells of the former yeast sown in 100 c.c. of saccharified 

 mineral nutrient solution increased to 140 million cells in fifty 

 days. Subsequently (II.) he extended the work by sowing 

 single cells ; but in twenty-one out of twenty-two tests no 

 development at all could be detected under the microscope, and 

 the only positive result (which was very scanty) was probably 

 due to the accidental introduction of a larger quantity of wort- 

 gelatin along with the cell used for inoculation. 



According to the observations of A. AMAND (II.), the amount 

 of bios in the nutrient solutions sown with yeast decreases very 

 rapidly, and can then no longer be demonstrated in the cells, at 

 least by the lixiviation method. J. HENRY (I.), on the contrary, 

 believed he had found yeast capable of forming new quantities of 

 bios, a capacity certainly possessed by other fungi (Penicillium 

 glaucum and a Mycoderma), as was first demonstrated by Kosso- 

 wicz (I.). Thus, saccharified mineral nutrient solutions in 

 which no development took place, owing to insufficient sowings 

 (in parallel tests), gave both reproduction and fermentation on 

 the Eumycetes in question being sown along with the yeast or had 

 been previously grown in the solution and then killed oft* by heat 

 before the introduction of the yeast. This observation, subse- 

 quently confirmed by A. AMAND (II.), is valuable in connection 

 with the interpretation of the results of previous workers. 

 Commercial pressed yeast and wine yeast are almost always 

 contaminated with Mycoderma, and the same is often the case 

 with brewers' pitching yeast. These Mycoderma, however, as 

 shown by WINOGRADSKY (XI.) and Kossowicz (with different 

 species), even in the case of rapid reproduction from a small 

 sowing, are able to satisfy their nitrogen requirements from ammo- 

 nium salts exclusively. Hence, when introduced with a sowing 

 of yeast into mineral nutrient solutions, they develop first, in 

 spite of their originally minute number, and then prepare the 

 nutrient medium in the above sense for the purposes of the 

 hitherto quiescent yeast. AD. MAYER (I.) also reports that in 

 his experiments (already mentioned on p. 542), " Mycoderma vini " 

 almost invariably appeared. Hence, as is now admitted, his 

 results do not apply solely to yeast, and show that the only way 



