172 EXPERIMENTS WITH PLANTS 



some coagulated white of <dg^^ and put in a warm 

 place. Keep as near the body temperature as pos- 

 sible. Place a little fibrin or white of ^^^ in water, 

 also some in acidulated water (1 cc. of hydrochloric 

 acid in 150 cc. of water) as controls. Place another 

 portion of coagulated white of ^gg in pancreatic 

 extract and keep in the same place. 



It should be noted that both the gastric and pan- 

 creatic juices contain ferments which coagulate the 

 proteid of milk (casein) : this is subsequently rendered 

 soluble. 



By the action of pepsin and trypsin the proteids 

 are changed into soluble substances which can readily 

 be absorbed by the cells. It is only natural to look 

 for pepsin and trypsin in seeds. In germinating Corn, 

 Barley and other seeds pepsin occurs, while in others 

 (Pea, Rye, Oat) it has not been found: it is natural 

 to suppose that in such cases other ferments take 

 its place. In certain plants which capture and digest 

 insects (Sundew, Nepenthes or Pitcher Plant) occurs 

 a ferment which resembles pepsin. 



One may easily ascertain the presence of a digestive 

 ferment in the juice of the Pineapple by expressing the 

 juice, filtering and placing a little fibrin in it (this, if 

 purchased dry, should be previously softened in water) . 

 Place a little fibrin in water as a control. The ferment 

 of Pineapple works best in alkaline or neutral solution 

 and hence resembles trypsin rather than pepsin. 



