104 ABSTRACTS 



cc. of milk, or less, is mixed with an equal amount of nutrient agar. 

 These "lilliputian" plates are incubated at 37°C. for from three to 

 twelve hours, depending upon the character of the milk. The little 

 plates are then air dried, fixed, treated with ten per cent acetic acid in 

 alcohol, stained in Loeffler's methylene blue (1:4), slightly decolorized 

 in alcohol, and dried. The colonies are stained a deep blue, while the 

 background is a light blue. 



The number of colonies in twenty microscopic fields is counted and 

 the number of colonies on the entire plate calculated. This number 

 multiplied by the dilution factor gives the number of bacteria per cubic 

 centimeter of milk. The magnification used should be from 100 to 200 

 diameters. Results of thirty-seven comparative tests are given. The 

 number of bacteria in these milks varied from 675 to 20,750,000 per 

 cubic centimeter. 



The correspondence seems reasonably close. The difference between 

 the two counts usually amounts to less than the differences which occur 

 between duplicate plates or the counts obtained by means of different 

 dilutions in the same analysis, or the counts obtained on the same milk 

 by different analysts. 



The preparation of the plates requires less time than the preparation 

 of the standard plates, the staining and counting a trifle more. No 

 expensive apparatus is required. The amount of culture medium is 

 very small. The time required to complete an analysis is never more 

 than twelve hours and in many, if not most, cases can be reduced to 

 four or five hours. 



Notes on Brine Pickle Fermentation. C. W. Brown. 



In salting cucumbers there may enter the tank many types of micro- 

 organisms; yet only those that can tolerate 12 to 20 per cent salt are 

 concerned in the normal fermentation. The acidity of new brine is 

 practically zero and increases gradually during two to six weeks to 50 

 per cent fo or above — a maximum of 75 to 100 per cent. The 

 principal acids are lactic and acetic in ratio of approximately 2: 1 with 

 traces of propionic, butyric, benzoic. During fermentation gases are 

 evolved; the volume is equal to approximately one-half the volume of the 

 tank and consists chiefly of carbon dioxid — 80 to 90 per cent; the samples 

 contained no hydrogen, no oxygen, a trace of methane and a residual gas, 

 presumably nitrogen. In the samples of brine analyzed alcohol was 

 found in traces only. 



The acid bacteria are facultative anaerobes, short rods or cocci ar- 

 ranged chiefly in chains of 2 to 5 members, they produce acid from glu- 

 cose and lactose, litmus milk after a time is rendered acid but is not 

 loppered. The ability to produce gas is questioned in that there is 

 evidence of the strains isolated producing sufficient gas to saturate 

 or nearly saturate the liquid medium. The gas formed during pickle fer- 

 mentation is produced largely by yeasts, which can tolerate the high 

 percentage of salt: However, motile short rods — colon type — may be 

 isolated frequently from brine during the first stages of the fermen- 



