DIGESTION OF ALBUMEN BY DROSERA 271 



other fungi. It appears to be excreted for the purpose of extra- 

 cellular digestion in the lower forms. The purpose of inversion 

 of cane-sugar is not known. 1 



Maltose and other sugars produced in the digestion of various 

 carbohydrates may be attacked by other enzymes beside those 

 named, at the time of their production, and as several fermenta- 

 tions may proceed simultaneously the chemical results are some- 

 what complicated. 



345. Digestion of Proteids. A number of enzymes are known 

 which act upon vegetable proteids, chiefly of the type of tryp- 

 sin. This exerts a hydrolytic action on proteids breaking them 

 into substances not to be classed as proteids, in contradistinction 

 to pepsin, a proteolytic enzyme abundant in animals and perhaps 

 present in a few plants. The products of pepsin fermentation are 

 soluble proteids, but the constitution of the proteid molecule is 

 so little known, that no statement can be made as to the chemical 

 changes ensuing during either tryptic or peptic fermentation. 



Tryptic fermentation usually ensues in the cells in which the 

 enzyme is secreted, and it has been found in many seeds and 

 fruits, accompanied in some instances by pepsin. It is excreted 

 and accomplishes digestion outside the body in bacteria, fung 

 and the carnivorous plants however. 



346. Digestion of Albumen by Drosera. The following experi- 

 ment by F. Darwin demonstrates the fermentative action of the 

 enyme secreted by the glandular hairs of Drosera. 2 



Cultivate a number of plants of any convenient species of Dro- 

 sera in shallow dishes or pots filled with sphagnum in a temperate 

 greenhouse. Cut a number of cubes of the white of a hard- 

 boiled egg about a millimeter in diameter, and select a few with 

 sharp corners and edges. Place one or two of these cubes of 

 albumen on each of several fresh young leaves where they may 

 be enclosed by the tentacles and lay a few of the cubes on the 

 moss near the plants. Examine the cubes a day later with a 



1 See Green, J. R. Sugar splitting enzymes. Fermentation, p. 105. 1899. 

 * Darwin and Acton. Physiology of Plants, p. 64. 1894. 



