DAIRY FARMING DAIRYING. 699 



■ lata included in this report are records of the yield and quality of the milk of 50 or 

 more cows of this breed. The average yearly yield of milk of 28 cows was 4,131.4 kg. 

 The average percentage of total solids was 13.16 and of fat 3.89. 



The cellular and bacterial content of cows' milk at different periods of 

 lactation, D. H. Bergey (Univ. Pennsylvania Med. Bui., 17 (1904), Nos.5-6,pp. 

 is 1-183). — The results of investigations in 1903 support the author's conclusion drawn 

 from earlier work (E. 8. R., 13, p. 587), that a high cellular and bacterial content 

 i >f milk is associated with some inflammatory process within the udder. The relation 

 of the period of lactation to the cellular and bacterial content of milk was studied in 

 the present investigation with 3 cows, one of which had contagious mamrnitis. 



In the present and earlier work the author has adopted the arbitrary standard 

 proposed by W. R. Stokes that the presence of more than 10 cells per field of 

 a T V immersion lens constitutes pus. When an average of 10 or more cells are pres- 

 ent in 10 fields, it is stated that the cells are usually more or less clumped, which is 

 believed to be an additional factor in the diagnosis of pus. A lower cellular content 

 than 10 is taken as the normal leucocyte content. Data obtained in this investiga- 

 tion are tabulated and the conclusions quoted below are believed to be warranted by 

 the results. It is stated that the detailed studies will appear in the Annual Report of 

 the Dairy and Food Commission for 1904. 



"The occurrence of pus in cows' milk is probably always associated with the 

 presence in the udder of some inflammatory reaction brought about by the presence 

 of some of the ordinary pyogenic bacteria, especially of streptococci. 



"When a cow's udder has once become infected with the pyogenic bacteria the 

 disease tends to persist for a long time, probably extending over several periods of 

 lactation. 



" Lactation has no causative influence per se upon the cellular and bacterial con- 

 tent of cows' milk, though it probably tends toward the aggravation of the disease 

 when the udder is once infected. 



"The so-called 'gelbe gait,' or contagious mamrnitis of European writers, appears 

 to be merely a severe form of mamrnitis due to a variety of streptococci!- which, on 

 account of its chromogenic properties, gives to the milk its peculiar golden- yellow 

 color. ' ' 



The initial contamination of milk, R. C. Newton (Jour. Amer. Med. Assoc, 43 

 (1904), No. 19, pit. 1387—1391). — Experiments are cited which are helieved to justify 

 the conclusion that no milk should be offered for sale which contains over 30,000 

 1 tacteria per cubic centimeter. The use of the covered milk pail as a means of lessen- 

 ing contamination is believed to be in the direction of simplicity and common sense. 



Study of formaldehyde in milk: Its germicidal action and the gradual 

 disappearance of it from the milk, D. Rivas I Univ. Pennsylvania Med. Bui., 1? 

 (1904), Nos. 5-6, pp. 175-180). — A relatively low number of bacteria in samples of 

 market milk, combined with negative results in chemical tests for preservatives, led 

 to a study of this subject. 



Five samples of milk were kept at a temperature of 6 to 8° C. 5 at 20 to 22°, and 

 "i at 37°. Each sample was divided into 2 portions, one of which was used as a con- 

 trol, while the other was treated with formaldehyde in the proportion 1:1,000; 

 1:10,00(1; l:2i).iMiii; 1:50,000; or 1:100,000. Bacteriological and chemical examina- 

 tions were made at frequent intervals. On the whole, formaldehyde showed a 

 decided germicidal action when used in the proportion of 1:1,000, some of the sam- 

 ples becoming completely sterile. Even when used in the proportion of 1:100,000 

 the germicidal action was constant although weak. 



As regards the disappearance of the formaldehyde from the milk, which was the 

 main purpose of the investigations, it was found that when the preservative had been 

 added in the proportion of 1:50,000 or 1:100.000. it had usually disappeared at the 



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