BtrliEAtf OF aniMal industry. ' ■ 95 



identifying the fecal bacteria have been much simphfied by a study 

 of the effect of the concentration of acid on the growth of bacteria. 

 An entirely new line of investigations of this nature has yielded 

 preliminary results of such promise that it has been considered 

 advisable temporarily to suspend work on the dysentery group, 

 started in cooperation with the Council of National Defense, until 

 more definite results can be obtained. 



A study of the different varieties of the colon-aerogenes group 

 of bacteria is being made in cooperation with a committee of the 

 United States Public Health Association by means of methods 

 developed in the Dairy Division laboratories. 



The possibihty of using the presence of fecal bacteria of the sporo- 

 gencs typo as an indication of the pollution by manure is being 

 stucHed. As the result a method of separating this type from 

 contaminating bacteria has been de^velopod, a description of which, 

 on account of its probable value in working with wound infections, 

 has been transmitted to the Medical Corps of the Army. 



In the studies of the Bacterium abortus type, which have been 

 completed, it was shown that there are two or more distinct but 

 closely related types of the organism, one of which is widely dis- 

 tributed but probably not pathogenic. Bacterium abortus was 

 shown to be either identical with, or at least closely related to, 

 the organism causing Malta fever. 



MILK SECRETION. 



In the studies of the changes in the nature and amount of phos- 

 phorus and calcium in the blood, it was possible to demonstrate 

 that the phosphatid of the blood plasma is reduced after passing 

 through the active mammary gland. The conclusion has been 

 drawn, therefore, that plasma phosphatid is the immediate pre- 

 cursor or forerunner of both butterfat and milk phosphorus. Prog- 

 ress has been made in determining just how the variations in the 

 various phosphorus fractions of the blood are produced and as to 

 what influence they have upon milk secretion, growth, and other 

 physiological processes. Evidence has been obtained supporting the 

 view that dairy cattle under ordinary conditions often suffer from 

 inability to absorb sufficient calcium and phosphorus to meet the 

 requirement of moderately heavy milk production. In preliminary 

 experiments the feeding of rations containing moderate c^uantities of 

 feed nutrients in such manner as to favor the absorption of calcium 

 and phosphorus has yielded such encouraging results that it is 

 desirable to repeat the work on a larger scale and under more 

 controlled conditions. 



8ILAGE INVESTIGATION. 



Studies of wood and concrete silos and of the nitrogen losses 

 in silage have been completed. As an incidental feature of the 

 latter investigation it was found that a coating of hot para "n served 

 as a perfect protection for cement against silage juices, and that 

 tar and asphalt paints were ineffective. An investigation is in 

 progress concerning the fermentation of silage that takes place 

 when crops are cut at various stages of growth. A study is also 

 being made of the availability of crops such as sunflowers and sugar 

 cane for silage. 



