404 The Physiology of Plants book hi 



that a theory of the course of the action was advanced, 

 when Musculus and Griiber suggested that the starch mole- 

 cule breaks down by a series of hydrations and subsequent 

 decompositions, maltose being formed at each splitting, 

 together with a dextrin of less molecular weight, until 

 finally all is converted into maltose. This view, with 

 certain modifications made by Brown and Morris in 1885, 

 was generally accepted. 



These observations were all made by means of experiments 

 -in vitro. In 1893 the present writer showed by treatment 

 of growing pollen-tubes with iodine that the same general 

 course of action can be observed in the living cell. Leclerc 

 du Sablon obtained similar results in the cells of the bulbs 

 and corms of certain Monocotyledons in 1898. 



The digestion of inulin was ascertained by the present 

 writer in 1887 to be effected by an enzyme, to which he gave 

 the name inulase. It was prepared from the germinating 

 tubers of the artichoke (Helianthus tuberosus). The products 

 of its action upon inulin were shown to be an intermediate 

 crystalline substance and a reducing sugar. Bourquelot 

 detected the enzyme in 1893 in the fungus Aspergillus, in 

 which it occurs mixed with several others, from which, 

 however, he was able to separate it. In the course of his 

 work he was able to prove that the reducing sugar is levulose 

 (fructose). Inulase was detected by the writer in 1900 in 

 the germinating bulbs of Scilla and Leucojum. 



The reserves of cellulose, which are met with in thickened 

 cell walls of the endosperms of various Palms and the 

 unchanged membranes of the endosperms of many of the 

 cereal grasses, were the subject of considerable research 

 by many investigators, and were in many cases shown 

 to be utilized through the action of cytase. Several pre- 

 parations of this enzyme were made, but some uncer- 

 tainty exists as to their identity with each other. Similar 

 bodies were found to play a part in fungal growth. The 



