DAIRY FAJRMING — DAIRYING. 287 



When fed under these conditions the addition of fat and of protein had always a 

 very favorable influence on milk production, though in an essentially different man- 

 ner, the f I fat being considered as exerting a specific influence on the formation 



of milk fat, while the protein showed no such specific action. The addition of car- 

 bohydrates was without influence <>n either the total yield of milk or the production 



of milk fat. The additional quantity of f I fat increased the refractometer number 



of the milk fat. Protein and carbohydrates showed no such influence. The varia- 

 tions in the live weight of the animals due to the supplementary food- was unimpor- 

 tant and warranted no definite conclusions. 



While not able to prove thai protein and carbohydrates have no Bpecific influence 

 in the production of milk fat, the authors believe from the results obtained in their 

 investigations to date thai food fat in quantities appropriate to the individual is espe- 

 cially suited to the formation of milk fat and, perhaps up to a certain limit, can not 

 be generally replaced 1>\ the other food constituent-. The reliability of the method 

 employed in making corrections for the decreased production of the animal- in suc- 

 cessive periods is also discussed. 



The chemistry of cow's milk, L. L. Van Si.vki: {Arch. Ped., ?2 1906 . No. .', 

 pp. 509-622) .—This discussion is based largely upon data obtained by the experiment 

 stations in the United States. 



"The knowledge thus furnished impresses one with the following facts: First, 

 analyses of milk, either averages or individual, furnish little real information unless 

 we know something of the history of the samples. Second, analyses made in other 

 countries may have little or n<> value when applied to milk produced in the CJnited 

 States. Third, any statement of so-called average composition of milk is misleading, 

 because normal cow's milk varies so much in composition, while many averages that 

 have been published are entirely misleadiug and thoroughly absurd." 



The author considers the nature and amounts of the different constituents in milk, 

 and suggests that in modifying milk for the use of infants and invalids the only way 

 that is really safe is to ascertain the actual content of fat and proteids in the milk to 

 be used for this purpose, rather than to take any average statement of composition as 

 a basis f( >r such modification. 



On the origin of lactose, ('. Porcheb {Compt. Rend. Acad. Sci. [Paris], 141(1905), 

 No. 1, pp. 73-7o). — In continuing his studies on the physiology of the mammary 

 gland I E. S. R., 16, p. 192), the author made use of 4 <:oats and 1 cow in full lacta- 

 tion, removing the mammary gland in each instance. The results are in accord with 

 those previously obtained, and indicate that the transformation of glucose into lactose 

 is an intramammary function. 



The detection and interpretation of the presence of ammonia in milk, A. 

 Trillat and Bauton I .1/'/'. Inst. Pasteur, 19 I 1905), No. 8, pp. 494-502). — As applied 

 to milk the nitrogen iodid test for ammonia, previously noted I E. B. R., 17, p. L13 . is 

 made preferably as follows: 



Ten rr. of milk is placed in a test tube and treated with 10 vr. of a 10 percent 

 solution of iodin trichlorid. The filtrate is neutralized carefully by the addition of 

 lime water, when in the presence of ammonia a Mack precipitate of nitrogen iodid 

 Boluble in an excess of the reagent is formed. A.ccording to the authors, as small a 

 quantity of ammonia as 1 in 100,000 may be detected in this way and approximate 



quantitative determinations made coloriinetricallv. 



The milk of healthy cows was not found to give this reaction. The authors then 

 investigated the conditions under which ammonia may be present in milk. Milk 

 Inoculated with sour milk and with typhoid, coli, anthrax, tubercle, and cholera 

 germs did not show the presence of ammonia during 72 hours. On the contrary, 

 milk inoculated with Micrococcus ureas, Tyrothrix tenuis, T. filiformis, Bacillus T'of 

 Flugge, sewage, and putrefying materials responded after some hours to the test. 

 So also did pure milk diluted with It) per cent of water from the Seine River. 



