ABSTRACTS 106 



tation and these bacteria produce hydrogen in no less quantity than one 

 part to three parts carbon dioxid. 



The scum yeasts or torulae which begin to develop upon the surface 

 of the brine during fermentation and later form a thick scum are 

 acid consumers. In wide mouth bottles plugged with cotton the acidity 

 of a 10-inch column of pickle brine was reduced from 74 per cent t^ to 17 

 per cent in 45 days at room temperature and to alkaline 12 per cent in 

 less than a year's time. Sterile pickle brine in test tubes inoculated 

 with pure cultures of the scum yeasts was reduced in acidity from 35 

 per cent w to neutral or alkaline within 30 days time at 20°C. The 

 first acid to be consumed is the lactic, leaving the acetic until the last, 

 that is, the ratio changes until the acetic is the predominant or only acid. 

 Tubes of pickle brine agar or even tubes of litmus agar to which sterile 

 commercial lactic acid is added — as much as 200 per cent t^ (1.8 per 

 cent pure acid) — when inoculated with these scum yeasts are rendered 

 neutral or alkaline adjacent to the growth of the yeast within a few 

 days' time. Under similar conditions acetic acid is consumed with 

 difficulty. 



The fermentation of brine pickles is an associative action of various 

 microorganisms resulting in (1) the using up of those constituents of the 

 cucumber which may be used readily as microbial food — protein made 

 soluble, sugar changed to acid, etc. — ; and (2) in preservation of the 

 depleted cucumbers (brine pickles) in the brine containing the by- 

 products. When the acidity which is a potent factor in preservation 

 is destroyed from the surface of the tank downward by the scum yeasts 

 the brine pickles are liable to decomposition. 



Sampling Milk for Bacterial Analysis. Robert S. Breed. 



In the series of comparative studies on the plate and microscopical 

 methods of counting bacteria in milk which are in progress at the New 

 York Agricultural Experiment Station, some tests of methods of samp- 

 ling have been carried out. In these tests, comparative counts have been 

 made in order to discover whether samples of milk taken in clean test 

 tubes containing preservatives (formaline or corrosive sublimate) were 

 as satisfactory for use in making microscopical counts as iced samples 

 taken in sterile tubes. The results secured are not sufficient to warrant 

 a positive statement but indicate that samples taken with preservatives 

 are as satisfactory as are the iced samples and much more convenient 

 to handle. When an effort was made to keep the preservative samples 

 for days or weeks, it was discovered that they became less satisfactory, 

 the longer they stood. This was not because the organisms lost their 

 staining power or because of any growth of organisms in the samples 

 but because the bacteria floated to the top with the cream which 

 became compact on standing. Some of them also fell to the bottom. 

 Because of the fact that it was impossible to shake a sample so as to 

 break up both the cream and the sediment perfectly, the counts secured 

 from the samples after standing tended to be lower than they should 

 have been. 



