188 ADULTERATION OF MILK. 



intended for human consumption, there is no necessity for 

 the use of preservatives to insure its keeping fresh. This is 

 particularly to be emphasized in the care of milk to be fed to 

 infants and invalids. 



While there is much evidence in favor of the use of some of 

 the preservatives for milk, such as boric acid or borax, formal- 

 dehyde, hydrogen peroxide, etc., yet most of this evidence is 

 the result of artificial digestion experiments. It is conceded 

 that such investigations are of great scientific value but too 

 much importance must not be attributed to them. There are 

 many conditions which obtain in the natural process of diges- 

 tion which cannot be duplicated under artificial conditions. 

 A notable instance of the necessity of conducting both the arti- 

 ficial and natural digestion experiments before drawing any 

 final conclusions is recorded by Wiley (6) in his report on the 

 influence of salicylic acid and salicylates on digestion and 

 health. 



Wiley states in his conclusions ; 



' ' The' data show very clearly that salicylic acid and salicylates appear 

 to exert an exciting influence upon the activities which take place in the 

 alimentary canal, stimulating the organs to greater effort, and this stim- 

 ulation leads at first to increased digestion and absorption of the foods 

 which are introduced into the stomach. In the light of the data which 

 are exhibited, salicjdic acid inay be said to increase the solubilitj' and 

 absorption of the food in the alimentarj' canal, so that large parts of the 

 nutrients taken into the stomach actually enter tire circulation. 



' ' The data which show the effects just noted also indicate that the 

 general effect upon the system is depressing, in that the tissues are bro- 

 ken down more rapidly than they are built up, and thus the normal 

 metabolic processes are interfered with in a harmful way. The admin- 

 istration of the salic\'lic acid is attended by a gradual decrease in the 

 weight of the subjects, altho tlie quantitj' of food elements administered 

 during the preservative and after periods is slightly increased, which 

 fact, together with a greater degree of absorption of the food elements, 

 should have resulted in a slight increase in weight. This increase in 

 weight, however, does not occur, and the disturbing influences of the 

 salicylic acid upon metabolism, altho not very great, are specifically 

 demonstrated." 



The natural inference from an artificial digestion experiment, 

 along the lines indicated, would be that salicylic acid is a 



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