204 THE PRESERVATION OF MILK. 



body. Even in the worst case, therefore, only the vegetative forms 

 (easily destroyed by boiling) of this microbe can find their way into 

 the milk from the body of the cow ; and, on the other hand, the 

 introduction of these germs from external sources is hardly to be 

 feared. According to the researches of O. CARO (I.), the virulence 

 of spore-free forms of growth of Bacillus anthracis in milk disap- 

 pears within twenty-four hours at a temperature of 15 C., a 

 circumstance attributable to the injurious influence of the lactic 

 acid gradually formed in that liquid. The spores, however, com- 

 pletely retain their vitality under these conditions. 



Among the bacteria present in unboiled milk, the species induc- 

 ing lactic fermentation are never lacking, and it is to these that 

 the souring of milk is due. The fact that they are destroyed by 

 boiling explains why boiled milk will keep, without alteration, 

 a much longer time than is the case with unboiled milk. In 

 addition to the species already mentioned there is present a third 

 group of Schizomycetes forming spores very tenacious of life, which 

 withstand boiling, and germinate when the milk is kept at a mode- 

 rately warm temperature. The resulting rods having, by the process 

 of boiling, been freed from the presence of sundry inconvenient 

 associates of other species, then develop and increase rapidly, 

 setting up a brisk fermentation whereby a large volume of gas 

 is liberated. The importance and extent of this fact first becomes 

 clear in the case of suckling infants. 



124. The Soxhlet Bottle. 



With the continual extension of enervation the number of 

 mothers unable or unwilling to suckle their infants increases from 

 year to year. How far the natural nourishment thus withheld is 

 superior, in point of chemical composition, in the various periods of 

 lactation to any artificial medley cannot be expounded here. From 

 the bacteriological standpoint it may be regarded as almost perfect. 

 If the mother be healthy in body, then the milk absorbed by the 

 child at the breast is, according to the researches of T. RINGEL (I.) 

 and others, almost entirely free from bacteria of any kind. The 

 expression " almost free " is used advisedly, since the milk gene- 

 rally contains a small number, originating in the air and making 

 their way into the lacteal ducts of the mammary glands, where 

 they increase. The necessary hygienic treatment of this organ 

 by the young mother will greatly contribute to the child receiving 

 the best nourishment both bacteriologically and otherwise. To 

 return, however, to those other matrons who bring up their infants 

 on the bottle, filled with boiled and sufficiently cooled milk. The 

 stomach of the young child being small, whereas the amount of 

 material required for the growing body is large, the infant requires 

 frequent supplies of small quantities of nourishment. Generally, 

 for the sake of convenience, a sufficient quantity of milk for the 



