1920.] PUBLIC DOCUMENT — No. 31. 41 o 



There is much else to be done before we shall be able to 

 complete our food investigations outlined three years ago, but 

 we are doing all that is possible with the help that is available. 



Dairy. — At the beginning of the academic year Mr. Roy C. 

 Avery began the study of streptococci in milk and milk prod- 

 ucts, butter and cheese, in association with his brother. Dr. 

 Oswald T. Avery, of the Rockefeller Institute for Medical Re- 

 search, who is studying streptococci in connection with diseases. 

 There is a wide field of investigation here which ramifies in 

 many directions having a practical bearing. Mr. Avery can 

 undertake only a very limited phase of the subject, but it 

 would be well worth the attention of the experiment station 

 to expand and continue the investigations in this field. 



The De Laval studies have been continued as rapidly as has 

 been possible under the circumstances. Prof. A. N. Julian has 

 reported on the difference in the content of carbon dioxide in 

 clarified and unclarified milk. Mr, Max Marshall has prepared 

 an article, which was presented at the recent meeting of the 

 Society of American Bacteriologists, on the association of 

 Bacillus siihtili-s and Streptococcus lacticus in milk. This work 

 pertains directly to the influence of the clarifier in disturbing 

 the germ-equilibrium of milk. Mr. John Yesair has contrib- 

 uted data which indicate the influence of a centrifuge or clar- 

 ifier upon different micro-organisms. 



The purpose of this work as a whole is to furnish an analysis 

 of what the clarifier does in the clarification of milk. A gen- 

 eral resume of this analysis has been published in the Amer- 

 ican Journal of Public Health. 



Mr. R, C. Avery is also at present engaged in studying the 

 influence of the clarifier upon the pasteurization of milk. 



Besides the above work there is work under way, upon 

 which we hope to be able to report some time, by Mr. E. G. 

 Hood, who is studying the colonization of bacteria in milk, 

 and b}^ Mr. James Neill, who is studying the influence of 

 Streptococcus lacticus upon certain protein changes in milk. 



Soil. — Dr. Arao Itano, in connection with Mr. L. C, Whit- 

 aker, is pursuing the study of microbial changes of organic 

 matter in the soil, confining himself at the present stage of the 



