AGEICTTLTUBAL CHEMISTRY AGBOTECHNT. 9 



enzym in the filtrate acts in part upon t±ie milk constituents, but the most 

 marked action of the filtrate is upon the lactic bacterium itself; two principles 

 of the filtrate are concerned in this, one destroyed and the other not destroyed 

 by heat. The former is most likely the pepsin-like enzym or the combined 

 pepsin and rennin, and the latter, certain food principles, possibly peptones, 

 produced by the yeast which are not changed by heating. . , . 



" The influence of the filtrate upon the virility of the lactic bacterium increases 

 directly as the amount of filtrated inoculum is increased ; this is true in the 

 heated as well as in the unheated filtrate. The filtrate both heated and un- 

 hented has a marked stimulating effect both upon the virility and upon the acid 

 production of weak lactic bacteria, which results in the rapid dying-out of the 

 lactic bacteria in the cultures to which the yeast filtrate has been added. [In 

 all probability] this effect may be attributed to the fact that the organisms 

 have been induced to produce nearly double their usual amount of acid, and 

 as a consequence have become hypersusceptible to their own products. . . . 

 It foDows then that a weak lactic bacterium will live much longer in pure cul- 

 ture in milk if no stimulant is added or if acid formation is prevented. [The 

 figures for] the hourly fermenting capacities of the weak lactic bacteria show 

 that the presence of the yeast filtrate, of the pepsin, or of the rennin solution 

 causes an increase of the fermenting power to nearly double that of the 

 check. . . . 



" The fact that the red yeast is a strict aerobe and lactic bacteria are facul- 

 tative, preferably anaerobes, accounts in all probability for one phase of the 

 beneficial associative action. It was proved quite conclusively that acid 

 introduced artificially or produced naturally in milk or whey is destroyed by 

 the yeasts, not merely neutralized. 



"After sojourning for some time with the different yeasts, the several lactic 

 bacteria were isolated and tested to ascertain whether the flavor of the curd 

 had been changed. These cultures were compared with the original pure cul- 

 ture, and no change had been effected. It is noteworthy that the mixed cul- 

 tures which have become contaminated with molds or other bacteria and yeasts 

 have not lost their power of retaining the vitality of the lacties except in one 

 instance. Foreign organisms seem to have no appreciable effect on the lactic 

 bacterinm and the yeast after the symbiosis of the latter had once been es- 

 tablished. 



" In the case of the mixed culture of the red yeast with different lactic bac- 

 teria, the lactic bacterium, even a very weak organism, has a chance to produce 

 its maximum amount of acid before any appreciable acid destruction can take 

 place. The high acid-producing organism used in the test, unlike B. bulgaricum 

 and ordinary lactic bacteria, survives a long sojourn at its maximum acidity 

 (in the neighborhood of +280°). The red yeast grows most difficultly with this 

 lactic organism. . . . 



" Many of the above statements are corroborative in their kind, of the con- 

 clusions drawn in Bacterial Associations in the Souring of Milk by Marshall 

 and Farrand [E. S. R., 20, p. 275] concerning the associative action of other 

 bacteria with lactic organisms. This phenomenon of associative action in time 

 may solve the problem of keeping other short-lived organisms almost indefi- 

 nitely without frequent transfers. 



" Further studies are being undertaken dealing with other phases of this 

 interesting problem." A bibliography is appended. 



Composition and properties of some casein and paracasein compounds, 

 and their relations to cheese, L. L. Van Slyke and A. W. BoswoBTff' (New 

 York State 8ta. Tech. Bui. 26, pp. S-S2). — This work was undertaken with a 

 "View of obtaining informatics regarding preparation and properti^ ot the com- 



