DAIRY FARMING DAIRYING. 185 



Bacteria were found in cultures from each of the udders examined. The possil)iHty 

 of air contamination as accounting for this result was excluded by a series of control 

 experiments in which pieces of sterilized paper were used in place of the animal 

 tissue, the results showing no infection, and by the conditions and results of the 

 experiments as a whole. The number of bacteria varied greatly in the different 

 udders and was highest in the two which were not examined until the morning 

 following the evening on Avhich the animals died, showing marked bacterial develop- 

 ment overnight. Plates exposed for from 10 to 45 minutes to the air of the 

 laboratory, in which the examinations were made, developed only 10 to 50 colonies, 

 showing an insufficient number in the air to account for the results. The cultures 

 did not show the diversity of forms to be expected from air contamination. More- 

 over, it was necessary to heat the gelatin to 37° C. in order to secure the liquefaction 

 of the gelatin and the penetration of the tissues in order to obtain a strong inocula- 

 tion, which would not have been the case had the bacteria been confined solely to 

 the exterior of the piece of tissue. 



The bacteria found were almost always liquefying and nonliquefying micrococci. 

 Occasionally, however, a nonliquefying Bacterium was present, and in 2 instances 

 other species, believed to be due to accidental infection, were met with. In 3 cases 

 portions of the. udder showed morbid changes, cultures from which, contrary to 

 expectiition, showed a low content of bacteria. In the udders of 3 cows, which had 

 not been milked for several weeks, fewer bacteria were present than usual. The 

 bacteria were apparently incapable of indefinite multiplication in the udder. 



The source of the bacteria in the udder was studied. Bacillus prodigivsMs injected 

 into the teat of a goat was recovered in the milk during the 8 days following. Three 

 days after a second injection the goat was killed and the bacillus was found in the 

 glandular tissue. B. fluorescens similarly injected was not recovered. "While not so 

 numerous as in the mammary gland, bacteria were also found in the normal kidney 

 and spleen, indicating an infection through the blood. The evidence so far obtained 

 is not considered sufficient to decide whether the infection of the mammary gland is 

 hematogenous or results from an invasion by way of the milk ducts. It is suggested 

 that perhaps the infection is produced in both ways. 



Studies concerning the so-called g-ermicidal action of milk, H. W. Conn and 

 W. A. Stocking {Rev. Gni. Luit, J [1903], Xox. 12, pp. 265-271; 13, pp. 298-304).— 

 The authors do not consider that the decrease frequently observed in the total num- 

 ber of bacteria in milk during the first few hours after milking is due to a germicidal 

 action possessed by the milk, but Ijelieve that certain species of bacteria, finding milk 

 an unsuitable medium for growth, disappear more or less rapidly, and that when such 

 species are more numerous than those finding milk a suitable medium a decrease in 

 the total number of bacteria may result. Evidence is presented in support of this 

 view, to which reference has j^reviously been made (E. S. R., 14, p. 533). 



The physical constitution of the fat globules of milk, M. Beau [Rev. Gen. 

 Lait, 2 {1903), Nus. 15, pp. 341-350; 16, pp. 372-378; 17, pp. 395-399; 18, pp. 417- 

 424; 19, pp. 441-448) . — This is an exposition of the different theories which have 

 been advanced, the evidence in support of each being reviewed in detail. 



Contribution to the study of churning, M. Henseval and L. Marcos {Rev. 

 Gen. Lait, 2 {1903), Nos. 20, pp. 463-469; 21, pp. 489-499; 22, pp. 519-524).— The 

 theory of churning is discussed and experiments relating to the influence of tem- 

 perature and rapidity of churning, richness of cream, acidity, and jjasteurization are 

 reported. The temperature and number of revolutions were varied in churning 3 

 lots of the same cream. With 60 i-evolutions and an initial temperature of 11° C. 

 the time required for churnmg was 58 minutes and the final temperature was 14.2°. 

 With the same number of revolutions and an initial temperature of 14° the time 

 required was 34 minutes and the final temperature was 15.2°. With 80 revolutions 

 and an initial teuiperature of 10° the time required was 62 minutes and the final 



