DAIRY FARMING DAIRYING. 873 



minor causes. These fluctuations range up toward a fifth of the cow's general 

 average richness, so that it is possible for a cow testing 5 per cent butterfat 

 in general to go down to 4 per cent and up to 6 per cent independently of time 

 of year, lactation period, and her own general course of change in richness. 

 Such extreme fluctuations are however very rare, half of these irregular ups 

 and downs being between — 0.2 per cent butter fat and +0.2 per cent butter fat, 

 four-fifths of them being between —0.4 per cent and +0.4 percent, and nearly 96 

 per cent of them between — 0.6 loer cent and +0.6 per cent. The fluctuations 

 up do not differ notably from the fluctuations down, but almost balance them 

 in every way. The nature of these temporary fluctuations in the butter fat per- 

 centage is such as to make it probable that they are due to the combined action 

 of many causes, each of which by itself alone would raise or lower the richness 

 only slightly. When it happens that a large number of the ' reducing ' causes 

 act at once and few of the ' increasing' causes, there is a large fluctuation down- 

 ward. Conversely, for the large fluctuations upward. Since such happenings 

 are necessarily rare, the large fluctuations are rare." 



The yield and composition of the milk of the Montgomery herd at Pusa 

 and errors in milk tests, J. W. Leather and A. C. Dobbs {Mem. Dept. Agr. 

 hidia, Chem. Ser., 3 (1914), No. 6, pp. 147-175).— In these tests, certain of the 

 cows appeared to yield more milk from one side of the udder than from the 

 other, although in general similar in both quantity and quality. There was a 

 difference found in both quantity and quality of the milk from the fore and 

 hindquarters which appears to be characteristic of the individual cow. One 

 cow yielded milk from the forequarter which was consistently richer than that 

 from the hindquarter, while another yielded richer milk from the hind than 

 from the forequarter, and a third showed no characteristic difference. It is 

 thought that the quality of the milk is a function of the tissue of that region 

 of the cow's udder in which it is produced and that though the opposite sides 

 are symmetrical in this respect, the udder is in other directions no more uni- 

 form in function than it is in shape. 



Tat content of milk and rate of coagulation with rennet, A. Kreidl and 

 E. Lenk (Biochem. Ztsclir., 63 (WW, No. 2-3, pp. 151-155, figs. 3).— The 

 authors found that the time required for the coagulation of a milk with rennet 

 is not constant even under similar experimental conditions. The rate of coagu- 

 lation varies with the fat content, and is smaller the richer the milk is in fat. 



Testing for fat in milk by the Babcock test (Illinois Sta. Circ. 174 (1914), 

 pp. 11, figs. 13). — Instructions are given for the use of the Babcock test. 



Bacteriological examination of market milk, P. G. Heinemann (Trans. 15. 

 Intemat. Cong. Hyg. and Demogr. Washington, 2 (1912), Sect. 1-2, pp. 133^ 

 135).— This gives the text of the article previously noted (E. S. R., 28, p. 275). 



Studies in bacterial metabolism, A. I. Kendall, A. A. Day, and A. W. 

 Walker (Jour. Amer. Chem. Soc, 36 (1914), No. 9, pp. 1937-1966) .—This con- 

 sists of a series of eight papers treating of the metabolism of various types 

 of bacteria in milk. The observations recorded were made for the purpose of 

 determining the nature and extent of the changes brought about by the growth 

 of various important types of bacteria in sterile certifled milk. . " These deter- 

 minations include the changes in reaction, as shown by alizarin, neutral red, 

 and phenolphthalein, which indicate somewhat roughly the differential accu- 

 mulation of alkaline or acid products, and the action on protein as represented 

 by the accumulation of ammonia, ammonia being the only available index of 

 protein breakdown applicable to this problem." 



Among the bacteria studied are those of the typhoid-dysentery-alcaligenes 

 group, intermediate or paratyphoid group, coli-proteus-cloacse group, subtilis- 

 mesentericus group, Bacillus pyocyaneus, B. diphtheriw, B. suipestifer, Vihrio 



