532 STATE BOARD OF AGRICULTURE. 



LITERATUKE REVIEW. 



In this review we liave iu mind the source and number of microor- 

 ganisms in cream and butter and their effect upon these products. The 

 microorganisms of milk are the microorganisms of cream. That the bac- 

 teria in milk are concentrated in the cream during their passage through 

 the separator is expressed by Stocking on page 318 of Marshall's Micro- 

 biology; the same has been demonstrated by the work of this laboratory. 

 This indicates that the types of organisms present in the milk are also 

 present in the separated cream. Evans (4) states that Bad. abortus is 

 an organism infecting cream and that in whole milk an abundant growth 

 occurs in the cream layer. The first possible source of bacteria in milk 

 is from the interior of the udder. Harding and "Wilson (G) state that 

 an average of 500 bacteria per c.c. can be ascribed as being in the milk 

 when it is drawn. They find, in their study of fifteen udders,. 71 groups 

 of miscoorganisms which are mostly micrococci. The most common or- 

 ganisms of the udder were found to be Micrococcus lactis albidus and 

 Micrococcus lactis varians. In one udder a non-liquefying yeast was 

 found in rather large numbers. About 30 per cent of these types of 

 microorganisms are slow liquefiers and the greater number of the re- 

 mainder are indifferent to milk. Hastings and Hoffman (8) found in 

 the milk of two cows throughout the lactation periods an average of 

 38,800 and of 30,700 bacteria per cubic centimeter respectively. These 

 organisms were streptococci, very similar in cultural and biochemical 

 features to streptococcus pyogenes, yet no gargety condition of the udder 

 was present during these investigations. These authors conclude that 

 the same organism may not only persist in the udder of a cow for long 

 periods but may be present constantly in large numbers. Esten and 

 Mason (3) made a bacterial study of material such as *'curry powder," 

 cow feces, hay, grass, ground feeds, soil, barn air, flies, etc., 

 which might gain access to milk thus forming a source of contami- 

 nation. On all of these materials microorganisms comprising a number 

 of types were found. Many of these from marked changes iu milk and 

 in the products obtained and manufactured therefrom.' In studying the 

 source of Bact. lactis acidi Esten (2) concludes that the cow's mouth is 

 a natural habitat and that any object or material reached by the tongue, 

 or saliva of the cow is well stocked with this bacterium. From these 

 various materials it enters milk where it is found almost constantly. 

 Occasionally this bacterium is found in the udder (3, p. 78), the pres- 

 ence of which can be accounted for in many cases by the contamination 

 of the teats with the saliva of a suckling calf (6, p. 38). Bact. lactis 

 acidi not being influenced by the germicidal properties of milk (15, pp. 

 15 and 20) increase in numbers from the very start. Gas producing bac- 

 teria, normal inhabitants of the alimentary tract, may be found in large 

 numbers on objects and materials which have been contaminated with 

 fecal matter. In a few instances members of this group of organisms 

 have been found in the udder (7, p. 3). From these sources, directly or 

 indirectly, nearly all milk is well supplied with gas producing bacteria ' 

 (7, p. 2) which multiply rapidly. Lewis and Wright (9, pp. 8-9) found 



