4-io The Physiology of Plants book hi 



and both animal and vegetable pl^siologists were sub- 

 mitting them to careful examination and scrutiny, filling 

 in the details of the schemes suggested, or accumulating 

 material for the discussion of their soundness. 



Even in this work botanists showed no great activity 

 till the seventies. The search for a proteoclastic enzyme 

 was first undertaken by Von Gorup-Besanez in 1874, and 

 such an agent was discovered by him in the seeds of the 

 vetch, hemp, flax, and barley. He described it as having 

 power to convert fibrin into peptone, but his examination 

 was not very detailed. 



The enzyme was rediscovered twelve years later by the 

 writer, who detected it in the germinating seeds of the 

 lupin in 1886 and in those of the castor-oil plant in 1890. 

 It was referred to the trypsins, as it was found to possess the 

 power of carrying the splitting of the protein as far as the 

 formation of amino-acids. The investigations were made 

 upon fibrin and also on the reserve proteins of the seeds, 

 giving us for the first time some information as to the fate 

 of the latter. Later in the century, in 1894, Neumeister 

 found that such an enzyme can be extracted from the 

 seedlings of the poppy, the rape, and several cereal grasses. 



These experiments were performed mainly in vitro ; it 

 was not till 1897 tnat E. Schulze showed that the course of 

 decomposition is the same in the living plant by his demon- 

 stration of the existence in germinating seeds of amino- and 

 amido-acids and characteristic basic bodies, resulting from 

 the digestion of proteins. 



Proteoclastic enzymes, whose purpose is not so imme- 

 diately evident as the trypsin of seeds, were discovered in 

 other parts of plants than seeds by Wiirz in 1879, Bouchut 

 in 1880, the present writer in 1892, and Chittenden in 1894. 



Wiirz's enzyme is known as papain and was prepared 

 by him from the fruit and juice of Carica papaya. It was 

 investigated with some completeness by Martin in 1883 



