412 The Physiology of Plants book hi 



It is worthy of mention again, that up to the end of the 

 century no adequate evidence had been obtained in favour 

 of the existence of a peptic as distinguished from a tryptic 

 enzyme in plants. 



The decomposition of fat during the digestive processes 

 is most easily studied in germinating seeds and it was to 

 them that attention was principally directed. The course 

 of such decomposition was, however, in many points largely 

 a matter of speculation at the end of the century. The 

 first inquiries made as to the fate of the fat in seeds were 

 due to Sachs, who in 1859 noted its disappearance during 

 germination. Observing a simultaneous formation of starch 

 in the tissue of the seedling, he somewhat hastily and with 

 less than his usual caution gave it as his opinion that the 

 oil was changed into the starch. Strange to say, this view 

 was for a time accepted, and prevailed without challenge 

 for some years. Fleury suggested sugar instead of starch 

 in 1865. 



The numerous discoveries of digestive enzymes directed 

 attention to the possibility of a hydrolytic splitting of the 

 fat under such agency, particularly when Muntz in 1871 

 ascertained that fatty acids appear in germinating seeds. 

 Such an enzyme was detected in the animal body by 

 Claude Bernard in 1849, an d its action was shown to be the 

 separation of fat into a fatty acid and glycerin. In 1876 

 Schiitzenberger observed that when oily seeds were bruised 

 in water and allowed to stand, both fatty acid and glycerin 

 could be recognised in their contents. The discovery of 

 the fatty acid led Detmer to the suggestion that it is the 

 antecedent of the starch observed by Sachs, a view which, 

 however, was not based upon experiment. 



The first stages of the decomposition were explained in 

 1889 by the discovery by the present writer of the enzyme 

 now known as lipase, in the endosperm of germinating 

 seeds of Ricinus. The course of the decomposition which 



