302 PHYSIOLOGICAL CHEMISTRY. 



organisms prevented, the formation of lactic acid may be entirely 

 stopped. The formation of acid may also be prevented, at least for 

 some time, by many antiseptics, such as salicylic acid (1:5000), 

 thymol, boracic acid, and other oodles. 



If milk is allowed to stand for a long time at a temperature of C. it re- 

 mains fluid for several weeks, but coagulates at last. In this case the coagula- 

 tion is not caused by the formation of lactic acid, but is more likely due to 

 the formation of fatty acids caused by an oxidation (HOPPB-SEYLER). 



If freshly-milked amphoteric milk is treated with rennet, it 

 coagulates quickly, especially at the temperature of the body, to a 

 solid mass (cheese), from which a yellowish fluid (sweet whey) is 

 gradually pressed out. This coagulation of milk occurs without 

 any change in its reaction ; it may also take place with the very 

 faintest alkaline reaction; therefore it is distinct from the acid 

 coagulation. 



Milk sometimes undergoes a peculiar kind of coagulation, being converted 

 into a thick, ropy, slimy mass (thick milk). This conversion depends, accord- 

 ing to SCHMIDT-MULHEIM, upon a peculiar change of the milk-sugar in which 

 this last is converted into a slimy product. This conversion is caused by a 

 special organized ferment. 



In cow's milk we find as form-elements a few colostrum cor- 

 puscles (see Colostrum) and a few pale nucleated cells. The 

 number of these form-elements is very small compared with the 

 immense amount of the most essential form-constituents, the milk- 

 globules. 



The Milk-globules. These consist of extremely small drops of 

 fat whose number is, according to BOHR, 2.6-11.4 or an average of 

 5.6 million in 1 c. mm. and whose diameter is 0.00014-0.0063 

 mm. (BOHR). It is unquestionable that milk-globules contain fat, 

 and we consider it as positive that all the milk-fat is found in 

 them. Another and disputed question is whether milk-globules 

 consist entirely of fat or whether they also contain albumin. 



According to an observation of ASCHERSON, the drops of fat are 

 covered with a fine albuminous coat, a so-called hapto gen-membrane, 

 when placed in an alkaline albumin solution. As milk on shaking 

 with ether does not give up its fat, or only very slowly by a great 

 excess of ether, and as this takes place very easily after the addition 

 of acids or alkalies which dissolve albumin, it was formerly thought 

 that the fat-globules of the milk were enveloped in an albuminous 



