80 V. H. YOUNG 



activity. Emulsin capable of hydrolyzing amygdalin, arbutin, 

 salicin, and phlorhizin is formed when sucrose is used as a source 

 of carbon. 



Dox also has carried out a series of experiments on the effect 

 of various carbohydrates on the formation of enzymes which 

 hydrolyze them, and finds that cultures of Penicillium camem- 

 berti grown with sucrose as a source of carbon yield very small 

 amounts of amylase. Enzyme preparations from cultures of the 

 fungus grown on sucrose, maltose, lactose, glucose, starch and 

 inulin all show some amylolytic activity, but that obtained 

 from cultures grown on maltose and more especially on starch 

 show the greatest amylolytic activity. 



Very interesting results were obtained by Dox in a study of 

 the inulase of the same fungus. The effects of sucrose, maltose, 

 lactose, starch, glucose and inulin on the formation of inulase 

 were determined. Digestion was continued for forty-two hours 

 at the end of which time the amount of inulin hydrolyzed is 

 found to be 92% by fungal preparations from cultures grown on 

 inulin and only 3% by all of the other preparations. 



Dox finds that ''the amount of the carbohydrate splitting 

 enzyms may be materially increased by cultivating the organ- 

 ism on the corresponding carbohydrate." This is particularly 

 true of inulase, amylase, and. lactase, which ordinarily occur only 

 in very small amounts. Dox further finds that ''there is no evi- 

 dence that enzyms not normally formed by the organism in 

 demonstrable quantities can be developed by special methods 

 of nutrition. The influence of adding a particular substratum 

 to the medium is, therefore, not to develop an entirely new enzym, 

 but to stimulate the production of the corresponding enzym 

 which is normally formed under all conditions." 



Boselli (1911) has studied the inulase of Aspergillus niger with 

 regard to the influence of carbohydrate nutrition on enzyme 

 secretion. Boselli evidently attempts in this work to take into 

 account both the enzymes present in the mycelium of the fungus 

 and in the culture medium. The mycelium after having been 

 removed from the culture flasks is washed and then ground up 

 with sand. The resulting mixture is allowed to digest for some 



