THE VITAL PROPERTIES OF THE CELL 151 



which acts upon carbo-hydrates, is present in some fission fungi 

 and moulds ; it splits cane sugar up into dextrose and levulose. 



The salivary ferment in the animal, ptyalin, which converts 

 starch into dextrin and maltose, corresponds to the diastase in the 

 plant. Similarly the non-diffusible glycogen, which in conse- 

 quence of its properties has been called animal starch, must, if it 

 is to be utilised further, be converted by means of a sugar-form- 

 ing ferment, wherever it occurs, into sugar (liver, muscles). 



Albuminous bodies are peptonised before they can be absorbed. 

 In the animal body this takes place chiefly by means of a ferment, 

 pepsine, which is secreted by the cells of the gastric glands. A 

 small quantity of pepsine is able either in the stomach or in a 

 test-tube to dissolve a considerable amount of coagulated albu- 

 men in the presence of free hydrochloric acid, thus converting it 

 into such a form that it is able to diffuse through membranes. 



Peptonising ferments have been also demonstrated in plant 

 cells. For example, one has been extracted in the form of a 

 digestive juice from those organs of carnivorous plants which are 

 adapted for the capture of insects, such as the glandular hairs of 

 the leaves of the Drosera ; in this manner the small dead animals 

 are partially dissolved and absorbed by the plant cells. A fer- 

 ment resembling pepsine has also been demonstrated in germi- 

 nating plants, where it serves to peptonise the proteid bodies 

 which are stored up as reserve material in the seed. The pepto- 

 nising ferment from the milky juice of the Carica papaya and of 

 other species of Carica is well known on account of its energetic 

 action. Finally, a similar ferment has been discovered in the 

 body of the Myxomycetes by Krukenberg. 



In the animal body fats are split up into glycerine and fatty 

 acids. This result is effected mainly by the pancreatic juice. 

 Claude Bernard endeavoured to trace this back to a fat decom- 

 posing ferment secreted by the pancreas. Further, it is supposed 

 that during the germination of fat-containing plant seeds the oils 

 are split up into glycerine and fatty acids by means of ferments 

 (Schiitzenberger) . 



Thus even from these few data it may be seen that, although 

 at present so little is known about the subject, there appears to 

 exist a far-reaching uniformity throughout the whole organic 

 kingdom as regards the elaboration of material in the cell. 



One of the points which is least understood concerning the 

 metabolism of the cell is the part played by the protoplasm. 



