128 V. H. YOUNG 



Organic food material is the most commonly recognized factor 

 in the stimulation of enzyme production. The numerous results 

 which all show that various organic sources of nitrogen and 

 particularly of carbon vary greatly in their power of stimulating 

 enzyme production have already been reviewed. It is commonly 

 recognized that the carbohydrate or other substance correspond- 

 ing to a particular enzyme causes that enzyme to be produced in 

 much larger quantities than do other substances. However, not 

 all investigators have found such a stimulatory relation exist- 

 ing between the substance and its corresponding enzyme. Katz 

 (1898) finds that starch alone is not so effective in stimulating 

 diastase production as when other substances more readily as- 

 similated are present in addition to it. Boselli (1911) finds that 

 all of the substances, which he employed as the source of carbon, 

 are equally efficient in stimulating inulase production. His re- 

 sults are strikingly at variance with the results of Dox and with 

 those described in this work. While in no case has there been 

 shown such a striking response to the stimulatory effects of inu- 

 lin as there was in the experiments of Dox, still without any ex- 

 ception inulin is found to be much more efficient than any of the 

 other substances used. As has been suggested before, the meth- 

 ods employed by Boselli (1911) are open to serious criticisms and 

 his results, for this reason, do not appear to be reliable. 



Not only do many organic foods have the power of causing an 

 increase in the amount of their corresponding enzymes over and 

 above what is produced under other conditions of nutrition, but 

 to a cerain extent, at least, the amount of enzyme produced ap- 

 pears to depend on the amount of the zymolyte present. As 

 stated before. Went (1901) found that within certain limits 

 many substances cause an increase in the formation of their cor- 

 responding enzymes when they themselves are increased. This 

 increase is not proportional to the amount of increase of the zymo- 

 lyte but is considerably less. Knudson (1913) has also shown in 

 connection with his studies of tannase that increased amounts of 

 tannic acid stimulate the secretion of increased amounts of tan- 

 nase. The results obtained in the experiments herein de- 

 scribed indicate that a similar result may be brought about with 



