igoSJ UPON HEALTH AND METABOLISM. 305 



evidences of decay and putrefaction, and, as a rule, stop most effec- 

 tively those fermentations which produce alcohol and carbon dioxid, 

 they do not have the same restrictive influence on those processes 

 resulting in the general degradation and decay of organic matter, 

 due chiefly to that class of chemical reactions which is represented 

 by the term hydrolysis. In other words, the ferments which break 

 down, for instance, nitrogeneous tissues into more soluble and finally 

 more dangerous forms of combination, are not so particularly in- 

 hibited as is the first class of ferments mentioned. 



This fact might well be used, however, as a justification of the 

 employment of chemical preservatives, since if they prevent the 

 ordinary processes of fermentation which produce evident indica- 

 tions of decay and putrefaction, it might be held that they would 

 not interfere with that other class of femientations or hydrolytic 

 processes peculiarly exercised by the digestive ferments. It will 

 probably not be contested at the present time that there is some 

 justification for this plea, since it has been well established that 

 an amount of a preservative which will for instance prevent alco- 

 holic fermentation will not interfere in anything like so serious 

 a manner with the action of such ferments as the diastatic fer- 

 ments of the saliva, of the stomach, and of the pancreas. On the 

 other hand, it is well established that in any notable quantities these 

 preservatives do interfere with even the latter class of ferments. 



But the problem which is of most importance in this con- 

 nection is, What is the chief efifect of these preservatives upon the 

 health of those who constantly use them and upon the metabolism re- 

 sulting from the normal functions of the body? To answer this 

 question, there was begun in an experimental way in the Bureau of 

 Chemistry, under my directioij, a few years ago, a series of studies 

 having for their purpose the elucidation of this problem. The gen- 

 eral plan of the experimental work was extremely simple. It con- 

 templated the selection of a number of young men between the ages 

 of twenty and thirty, in excellent health, who had suffered from 

 no serious disease in the immediate past, who were of steady habits, 

 who were not addicted to the use of alcohol, and whose character 

 was such as to warrant especial confidence and trust in their 

 veracity and general conduct. Such voung men evidently are to be 



