98 ANNUAL EEPOETS OF DEPARTMENT OF AGRICULTURE. 



and practical application in general. Some work of the latter 

 nature too technical to be described in this report is in course of 

 publication. 



A study of streptococci from sour milk, feces, and the udder has 

 resulted in the working out of methods for separating and distin- 

 guishing these organisms, and has shown the existence of a typical 

 lactic streptococcus. Media which promise to be of considerable 

 ^alue in bacteriological technique have been developed by the sub- 

 stitution of yeast extract for the usual beef extract. Progress has 

 also been made in developing a test for quality of milk through 

 work with sporogenes. 



MILK SECRETION. 



Further studies on milk secretion have demonstrated that there is 

 a close relation of the phosphorus and calcium content of the blood 

 to the milk-producing function. It has been shown that a deficiency 

 of phosphorus in the rations for cows and calves has a detrimental 

 effect on milk secretion and growth. A remedy for this condi- 

 tion was found in the addition of sodium phosphate to rations 

 deficient in phosphorus. Work with dairy cows has shown that the 

 feeding of phosphorus and calcium results in a decided beneficial 

 effect on the milk flow, in both amount and fat content. Balance 

 experiments have shown also that the conditions under which it is 

 necessary to keep coavs Avhile conducting work of this kind have a 

 disturbing effect on the digestive processes. This observation calls 

 for improvements in equipment used in the future. 



CONDENSED AND EVAPORATED MILK. 



Investigations have been undertaken with various forms of con- 

 densed and evaporated milk, with the general purpose of improving 

 the phj^sical condition and keeping qualities of these products. 

 Studies on the curdling of evaporated milk in sterilizing have been 

 continued, and progress has been made on the problem of preventing 

 the thickening of sweetened condensed milk on standing. 



The theoretical sugar solution required to inhibit bacterial growth 

 in the condensed milk has been determined within narrow limits. A 

 study of the bacteria and yeast which might be involved in these 

 changes has resulted in increased knoAvledge of their behavior. 



Work with certain molds has positively demonstrated that the 

 " buttons " of condensed milk are caused by this growth. Further 

 results have shown that in commercial production the condensed milk 

 may be produced without danger from molds if sealed under the 

 vacuum produced by the ordinary vacuum pump. 



Tests to determine the suitability of milk for condensing purposes 

 indicated that neither the acid test alone nor the alcohol test alone 

 nor a combination of the two was satisfactory, 



ICE CREAM. 



A substitute for a large part of the cane sugar in ice-cream mak- 

 ing was found through experiment, and the formula was widely 

 disseminated. The preparation of pure butterfat for ice cream and 

 reconstituted milk has not given satisfactory results. 



