ooc I VoL - 6 



^ZO ANNALS OF THE MISSOURI BOTANICAL GARDEN 



There has, in general, been agreement among investigators 

 as to the occurrence of diastase in plant tissues, but a notable 

 exception in this respect was Wortmann ('90), who concluded 

 from his experiments that the dissolution of starch in plants is 

 brought about directly by the protoplasm and independently 

 of the diastase present. This conclusion was based on experi- 

 ments made by him which showed diastase to be absent from 

 most leaves, and to occur in others in such small quantity and 

 in such a state as to exhibit only very feeble activity. Even in 

 those cases where this slight activity was manifested it would 

 not, according to him, account for the transformation of starch 

 which actually takes place. 



It is of interest in this connection to note that Schimper 

 ('85) had found that starch-free leaves of Allium were much less 

 diastatically active than the leaves of Tropaeolwn, which contain 

 much starch. The comparatively recent work of Bradley and 

 Kellersberger ('12) in this particular should also be mentioned. 

 They found that the leaves of many different species of plants 

 varied greatly in their diastatic content, some, such as the bay- 

 berry, onion, and leek, giving so little reaction as to make the 

 presence of the enzyme doubtful. 



Brown and Morris ('93) could not agree with the theory of 

 Wortmann, referred to above, that the protoplasm and not an 

 enzyme is directly responsible for the transformation of starch 

 in leaves, but believed, as did Baranetzky, that diastase is univer- 

 sally present in these organs, and that dissolution of starch is 

 brought about by it. They criticized Wortmann's work, chiefly 

 on the ground that he used the clear filtered leaf extracts in his 

 experiments and did not take into consideration the tannins of 

 the leaves, which they found to interfere greatly with the 



d 



The clear filtered leaf 



extract was found by them to possess much less activity than 

 the same extract before filtering. 



This work of Brown and Morris is perhaps the most compre- 

 hensive and conclusive that has been carried out upon the 

 presence of diastase in plants. They determined the activity 

 of the enzyme in all cases by the addition of .5 gm. of finely 

 powdered, air-dried leaves to 50 cc. of a 2 per cent starch solution 



