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MCGINTY — DIASTASE ACTIVITY OF SOLANUM TUBEROSUM 229 



starch of other leaves. He found that plants which store starch 

 abundantly contain comparatively little soluble reducing and 

 non-reducing carbohydrates in their leaves, while others, such 

 as Allium Cepa, Iris germanica, and Gentiana lutea, which store 

 no starch, accumulate relatively large quantities of soluble 

 reducing substances in their leaves. These reducing substances, 

 according to him, appear to be regulated by the same laws as 

 starch in relation to their appearance and disappearance in 



light and darkness. 



The formation and distribution of diastase in the potato 

 tuber was investigated by Prunet ('92), who observed during 

 germination that diastase activity was greater toward the 

 "seed end" of the potato than elsewhere. This corresponds 

 with the greater development of shoots from that region. He 

 found also a correspondence between the sugars present in the 

 different portions of the tuber and the amount of diastase. 



Green ('99) states that in some experiments carried on by 

 him in 1893 he found diastase to be present in the pollen of many 

 plants. The amount usually increased considerably at the on- 

 set of germination, and appears, it is stated, "to accompany the 

 tube as the latter elongates, which suggests a formation not only 

 in the grain but in its tube also." As the pollen loses with age 

 the power of germination, it also loses its diastase, which is an 

 indication of the part played by the enzyme in germination. 

 This, Green suggests, is comparable with the influence exerted 

 by diastase in the germination of the potato. 



The effect of enzymes upon seed germination was the subject 

 of some study by Waugh ('98). Employing solutions of diastase 

 and some other enzymes, he found that the percentage of ger- 

 mination of old tomato seed was considerably increased, in the 

 case of diastase, where the seeds were soaked in the solution for 

 several hours. Taka-diastase gave somewhat higher, but not as 

 uniformly favorable, results as malt diastase. Trypsin also 



some 



/ on the formation of sugars and starch 

 led him to believe that in the very immature 



tubers the sugar might be 



dependent perhaps upon meteorological conditions. He found 



