174 EXPERIMENT STATION RECORD. 



affected by coagulation with rennet is tlie same as that of the soluble proteids 

 in the milk. Coagulation is believed to be explainable only as a physical phe- 

 nomenon. 



The globulin of milk, L. Morochowetz (Phijsiol. Russe, .'/ {1906), No. 68- 

 7.'i. iqj. JjS-'JG). — This is an extended review of the literature of milk proteids, 

 all of which are considered by the author products of one and the same sub- 

 stance, designated lactoglo))!!!. 



Upon the reduction of methylene blue by cow's milk, E. P. Cathcart 

 {Join: Hiig. [Vaiiihriduc], (J {l'.H)6), No. 3. pp. 300-303). — Raw milk decolorizes 

 a mixture of formalin and methylene blue, depending upon the action of catalase 

 in the milk. As this ferment is destroyed by heating to 65 to 70° C, this test, 

 known as Schardinger's, serves well to differentiate between heated or boiled 

 milk and raw fresh milk. It has been suggested by H. Smidt that a further 

 use might be made of this test as a means of determining the degree of bacterial 

 contamination of milk. 



In studying the possibilities of this test the author ascertained that in order 

 to get reliable and constant figures a very definite temperature must be em- 

 ployed. A rise in the temperature of the water bath from 40° to 50° was 

 found to cause a diminution of practically 50 per cent in the time required for 

 reduction. Another possible source of error arises from the fact that the 

 catalase is found almost completely in the cream and hence a sample taken 

 from the bottom and another from the top layer of milk that has been allowed 

 to stand for some time would show a marked difference in results. This re- 

 action is also affected by heat and the age of the milk, the latter due probably 

 to the increased bacterial content. Earlier experiments in which the author 

 cooperated showed that the reducing action of organisms varies to a marked 

 degree. 



In view, therefore, of the many possible sources of error the author considers 

 this test as a means of estimating the bacterial contamination of milk too 

 delicate for ordinary use, but that it might possibly be of value in a large 

 laboratory where the various sources of error could be readily eliminated. 



Quality of milk affected by common dairy practices, W. A. Stocking, Jr. 

 {Connecticut titorvs 8ta. Bill. .'/.?, pp. 62-90, figs. 2, dgms. S). — This bulletin gives 

 the results of a large number of experiments made to determine the effect upon 

 the bacterial content of milk of some common dairy practices, such as feeding 

 dry feeding stuffs at milking time, wiping off the cows with a damp cloth or 

 brushing them at milking time, rejecting fore milk, etc. 



The bacterial content of the milk was greatly increased by giving dry feeds 

 just before or at milking time. This was more marked in the case of corn 

 stover than hay or grain. Wiping the flanks and udder of the cow with a damp 

 cloth just before milking was very efiieient in reducing bacterial contamination, 

 while brushing the cows at this time increased the germ content of the milk. 

 Thorough stripping reduced the number of bacteria found in the milk at the next 

 milking. Rejecting the fore milk reduced slightly the germ content of the 

 remaining milk, but the difference was so small that the practice is considered 

 as probably of value only w^here an extremely low germ content is desired. 



Several experiments were made to determine the extent to which individual 

 milkers affect the germ content of the milk. Five students trained in dairy 

 bacteriology and the production of clean milk were compared with 2 regular 

 milkers. Although stable conditions were identical and the same procedure was 

 followed in each case, there was an average difference of 1,932 bacteria per cubic 

 centimeter in favor of the students. A college graduate in charge of the dairy 

 herd was also compared with the regular milkers. In this case the difference 

 in the bacterial content of the milk as an average of 19 tests was 14,650 bacteria 



