7r)8 EXPERIMENT STATION RECORD. 



" (8) Washing the machiues with cold water aud then with hot water con- 

 taining sal soda is not sufficient to keep the rubber tubes clean. Under this 

 treatment the inside of the tubes becomes coated with decaying milk, thus form- 

 ing ideal conditions for the multiplication of various species of bacteria. 



" (9) Scalding the machines by pumping boiling water through them just 

 before use had little or no effect in reducing germ content of the milk. 



" (10) Boiling in clear water for three-quarters of an hour was mjt sufficient 

 to keep the rubber tubes in a sterile condition. 



" (11) Subjection to steam without pressure for ;i() minutes was not suffi- 

 cient to sterilize the I'ubber tubes. 



" (12) Placing the rubber parts in brine for several hours after being washed 

 reduced the germ content of the machine-drawn milk to about one-half that of 

 the milk drawn by hand. 



"(13) Boiling in water containing a. small amount of powdered borax had 

 about the same effect in reducing the bacterial content of the milk as did the 

 brine treatment, but the use of borax is dangerous unless extreme care is 

 exercised. 



"(14) The machines may l)e very effective in the production of sanitary milk 

 if they are properly cleaned and sterilized. 



"(15) The results of these experiments indicate that the machines may be 

 kept in such an insanitary condition that the keeping quality will not be im- 

 proved, but may be seriously impaired. They also indicate that with properly 

 cleaned and sterilized machines the keeping quality of the milk may be very 

 materially improved." 



The variation in the composition of milk, A. Lauder (Ediiib. aiifl East of 

 Scot. Col. Af/r. Bill. 11, pp. 52). — Causes of variation in the composition of milk 

 are briefly discussed, and the results of a systematic examination of the milk of 

 two well-kept private dairy herds in the East of Scotland are reported. The 

 investigation with one herd of 22 cows begiin in May, 1905, and is being con- 

 tinued. Another herd of oO cows was tested from June to October. 1905. Both 

 herds were of the dairy Shorthorn type. 



The average composition of the mixed milk of the smaller herd for 1 year 

 was 12..34 per cent of total solids and 3.15 per cent of fat for the morning's milk, 

 and 12.96 per cent of total solids and 3.91 per cent of fat for the evening's milk. 

 The cows were milked at 6.30 a. m. and 4 p. m. During the months of February, 

 March, and April, the milk of individual cows fell below the legal standard of 3 per 

 cent of fat 99 times in the morning and 45 in the evening. When the cows were 

 milked at equal intervals for a short period the dift'erences in percentages of 

 fat and total solids between the morning's and evening's milk were nuich reduced. 

 Increasing the amount of feed had iiractically no eft'ect on the fat content of 

 the milk. 



The average composition of the mixed milk of the other herd was 12.83 per 

 cent of total solids and 3.95 per cent of fat for the morning's milk and 12.77 

 per cent of total solids and 3.88 per cent of fat for the evening's milk, but here 

 the intervals between milkings were equal. 



Opsonins in milk, G. S. Woodhead and W. A. Mitchell {.four. Path, aitd 

 Bad., 11 (i,907), Xo. J/, pp. .'/OS-J/l'i) ■ — Using human leucocytes the opsonic index 

 of the blood of a nontuberculous cow was found to be O.S and that of the milk 

 0.6. The figures in another case were, respectively, 0.96 and 0.57. The milk of 

 an apparently healthy cow showed an opsonic index of 2.2, while the indices 

 of the milk of 3 cows in a comjiaratively low state of health were, respectively. 

 0.51, 0.44, and 0.48. The oi)sonin content of whey ])rei)ared by either rennet 

 or hydrochloric acid was found to be greater than that of an equal volume of 



