990 EXPERIMENT STATION RECORD. 



utes at 60 to 70 C. Finally, it was found that the rennet of frogs was 

 more adive at low temperatures than that of man and calves, although 

 at medium temperatures the latter was the more active. 



Concerning the relation between the amount of rennet and the time 

 of curdling it was found that these were proportional only within 

 narrow limits, and that, in general, where large quantities of rennet 

 were used the curdling took place more slowly. 



The remainder of the experiments related to studies of rennet zym- 

 ogen, the amount of rennet in the lining of the stomach under different 

 conditions of nutrition, etc. The results are briefly summed up as 

 follows: The content of rennet euzym in the lining of the stomach is 

 very low in both fasting and digesting animals, but is greater in the 

 case of tasting animals. The content of zymogen is considerable, 

 whether the animal is fasting or digesting food. 



Tainted or defective milks, their cause and methods of prevention, II. L. 

 Russell (Wisconsin Sta. Bui. 02, pp. 27, figs. 10).— In this bulletin the author treats 

 in a popular manner the established facts relating to the cause, nature, and preven- 

 tion of taints. Taints are divided under two general heads— (1) those produced by 

 living organisms, and (2) those due to the absorption of odors or to the derangement 

 of the normal functions of the animal. By way of introduction, the bacteria of milk, 

 the manner in which they get into milk, effect of temperature on their growth, etc., 

 are discussed in a quite general way. Following this various specific fermentations, 

 causing taints in milk and cheese, are described and illustrated. The direct absorp- 

 tion of taints beforeand after milking, the discrimination between directly absorbed 

 and biogenic taints, treatment of tainted milk, and the method of eliminating taints 

 are treated in logical order. In conclusion, a valuable list of suggestions is given 

 for producers in regard to the care of milk, covering the care of animals, milking, 

 storage and transportation of milk, and care of utensils. 



"In caring for milk it should be remembered that two things are necessary: 



"(1) To prevent the absorption of any foul odors. 



" (2) To prevent the development of living organisms in the milk that are able to 

 form foul substances that taint the same. 



"The iirst can be accomplished by keeping taint-producing feeds from the cow 

 and by keeping the milk in a place that is free from all undesirable odors. The 

 second result can be attained by thorough cleanliness combined with a low 

 temperature." 



Government aid to dairying in Denmark, B. BOGGILD ( Ugeakr. Landm., 42 {1897), 

 Nos. 28, pp. 361-364; 29, pp. 376-379). 



Milk: Its decomposition and preservation, R. R. Dinwiddie (Arkansas Sta. 

 Bpt. 1897, pp. 49-77, pis. 3, figs. 3). — A reprint of Bulletin 45 of the station (E. S. R., 

 9, p. 689). 



Bacteria and the dairy, C. E. Marshall (Michigan Sta. Bui. 146, pp. 19). — A popu- 

 lar bulletin on this subject, treating of the fermentations of milk, means of infection, 

 use of pure cultures, etc. 



Annual report of the office for chemical examinations in Breslau (.lbs. in 

 Milch Ztg., ?6 ( 1897), Xo. 35, pp. 558-560). — During the year 340 samples of butter were 

 examined, of which 34, or 9 per cent, were regarded as suspicious, usually ou account 

 of high water content, high salt content, or being in a spoiled condition. The stand- 

 ard fixed for the city since 1896 has been not over 3 per cent of salt, 15 per cent of 

 water, and in doubtful cases at least 80 jier cent of fat. It is believed that normal 

 butter should not contain more than 15 per cent of water. The analyses are given 

 of a number of samples of butter with a high salt content, with a high water con- 



