268 EXPERIMENT STATION EECOED. 



By the Hegelund metbod the cow is milked every two or three hours for the 

 first few days after calving, and then Ave times per day for three or four 

 weeks. 



The effect of pituitary extract on milk secretion in the goat, R. L. Hill 

 and S. Simpson {Quart. Jour. Expt. Physiol., 8 {19U), No. 2-3, pp. 103-111, 

 fig. 1; abs. in Lancet [London], 191^, II, No. 12, pp. 753, 75^).— As the result 

 of their researches, the authors have found that " intravenous or subcutaneous 

 injection of the extract obtained from four ox pituitaries produced a marked 

 increase in the amount of mammary secretion of a goat when milked 15 minutes 

 after injection. A corresponding decrease below normal follows at the next 

 milking several hours later. As pointed out by Hammond [E. S. R., 31, p. 272], 

 there is also a marked rise in fat content in the milk secreted after injection, 

 but there is no sudden fall in the fat percentage at the next milking, as was 

 observed by this investigator. The solids-not-fat of the milk appear to be 

 unaffected by the extract." 



Dairy bacteriology, C. L. Roadhouse {California Sta. Rpt. 1914, P- 184)- — 

 From examinations made by R. S. Adams of 100 samples each of milk, skim 

 milk, and cream, coming from different sources, it is concluded that " the pro- 

 portion of bacteria distributed from whole milk into skim milk and cream by 

 means of a centrifugal separator varies in different classes of milk. The skim 

 milk and cream resulting from the separation of fresh certified milk each had 

 a bacterial content about equal to that of the original milk. The skim milk 

 resulting from the separation of fresh market milk contained 29.5 per cent 

 less bacteria per cubic centimeter and the cream 51.4 per cent more bacteria 

 than the milk from which it was separated. When old market milk was sepa- 

 rated, the resulting skim milk contained 15 per cent less bacteria and the 

 cream 25 per cent more bacteria than the whole milk." 



Observations upon the bacteria found in milk heated to various tem- 

 peratures, W. W. Ford and J. C. Pbyob {Bui. Johns Hopkins Hosp., 25 {1914), 

 No. 283, pp. 270-276). ■ — ^The authors have attempted to confirm the earlier 

 findings of FKigge to the effect that "milk always contains the heat-resistant 

 spores of aerobic and anaerobic bacteria, which, by their development, can give 

 rise to disagreeable and unwholesome changes in milk, converting it from a 

 food of great nutritive value into an undesirable if not a dangerous article of 

 diet." 



In a study of 78 samples of Baltimore milk, representing 21 different dairies, 

 it was found that " these changes take place in milk heated to any tempera- 

 ture from 65 to 100° C. and kept at any temperature from 22 to 37°, but not 

 at that of the ice box, 4 to 6°. The spores of the bacteria causing these changes 

 survive in milk for long periods of time on ice and can initiate the same 

 changes in milk kept on ice when transferred to higher temperatures. There 

 is a danger zone in the heating of milk which may be described as ranging 

 from about 65 to 85° in which milk will never clot normally. Below this 

 temperature heated milk may clot normally. Above this temperature milk will 

 either clot or slowly peptonize. 



" The problem of pasteurization of milk must be worked out on the basis of 

 the changes which occur in milk heated to 60 to 65° and the result may de- 

 pend upon the original character of the milk, upon local bacterial infections of 

 milk, on the character of the stables in which the milk is first obtained, upon 

 methods of preservation, or upon unknown factors. Further investigation 

 alone can determine these points. With our present knowledge as to the diffi- 

 culty of getting milk free from pathogenic organisms the safest milk is that 

 which has been boiled for a time varying from ten minutes to half an hour 



