64 MILK AND ITS HYGIENIC RELATIONS 



gland manufactures certain chemical substances differing in composi- 

 tion from those manufactured by other organs, the secretion also con- 

 tains traces of waste products which have passed out from the blood- 

 vessels in small amounts, so that the secretion also contains some 

 substances which have been derived from the blood by filtration. 

 Every living cell contains ferments, and every animal organism 

 depends for its existence upon the action of ferments. Digestion, 

 leading to the assimilation of digested food-stuffs, and the inter- 

 change of nutritive material in fact, most of the processes connected 

 with the metabolism or life of a cell are due directly or indirectly 

 to the action of ferments. This being the case, it is unreasonable 

 to suppose that ferments do not exist in every part of the body. 

 There is considerable variation in concentration of the ferments, 

 but the fluids of the body, practically without exception, contain 

 ferments of one kind or another. 



As far as is at present known, each ferment performs one action, 

 and one action only that is to say, it is adapted for working 

 upon and effecting an alteration in one particular chemical substance 

 only. A ferment which will attack a fatty substance has no effect 

 whatever upon a substance belonging to the class of starches or 

 sugars. Each ferment, therefore, is said to be ' specific ' in its 

 activity. Evidently there must be a great number of ferments, 

 each of which fulfils its own part in the life of the animal organism. 



Ferments are produced by animal cells and by bacteria. 

 Actions identical in their effects with those due to certain ferments 

 are also caused by certain metals, when these are in colloidal 

 form. Thus spongy platinum will break up hydrogen peroxide, 

 with the evolution of oxygen, in the same way that this substance 

 is split by the ferment catalase, which is found in the blood and 

 in the tissues. 



Ferments are present in every cell of the mammary gland. It is 

 known that these cells break down and disintegrate in the course 

 of milking and of milk production, since portions of cells can always 

 be found, together with intact cells, in the sediment from any sample 

 of milk. It is impossible to suppose, therefore, that ferments would 

 not be found in the milk owing to the presence of these portions of 

 disintegrated cells. Moreover, the blood and lymph, carrying the 

 nutritive substances to the cells of the mammary gland, contain 

 ferments and, as in the case of the other secretory glands, traces 

 of substances find their way through from the blood and lymph 

 into the secretion of the gland, in this case into the milk. 



There is abundant evidence to show that ferments of various 

 kinds are present in milk, and that these ferments differ, both in 

 quantity and also in quality, in the milk of different species. In 

 addition to the ferments derived from the gland itself, ferments 

 are frequently introduced after the milk has been collected. This 

 is due to the presence of bacteria in the milk, the bacteria having 

 been derived from the air or from the cow herself, or from other 



