BOTANY. 117 



similar to that which has been observed upon the life of microorganisms 

 and other low forms of vegetation. 



The method of investigation was to expose various solutions contain- 

 ing diastase to the action of light for several hours, and after such 

 exposure to test their hydrolyzing power upon a weak solution of solu- 

 ble starch or upon a 1 per cent starch paste. The diastatic solutions 

 used were extract of malt, solution of diastase precipitated from malt 

 extract by alcohol, dilute saliva free from mucin, and extract of foliage 

 leaves. The source of illumination was either bright sunshine, diffused 

 light, or naked electric are light. 



From repeated experiments it was found that exposure to the whole 

 spectrum for several hours caused the destruction of from 20 to GO per 

 cent of the diastase. When the ultraviolet rays were cut off by the 

 intervention of glass, at first there was a considerable increase of the 

 diastase, but this was succeeded on a longer exposure, lasting for 

 several days, by a gradual and almost complete destruction of the 

 enzym. By the use of a series of screens the visible spectrum was 

 divided off and the effects of the different regions tested, the details of 

 the experiments being given in the complete paper. It was found that 

 the infra-red, red, orange, and blue regions gave an increase of 10.8, 

 53.5, 4.75, and L'0.8 per cent, respectively, and the green a diminution 

 of 15.7 per cent. The effect of illumination upon diastase was found 

 to be progressive, the increase or diminution continuing after the solu- 

 tions were removed from the influence of the light. The screening 

 influence of proteids was examined by adding small quantities of egg 

 albumen to the extracts, and were found to be protective about in pro- 

 portion to the amount of albumen present. The coloring matter in 

 barley grain was also ascertained to act as a screen against the dele- 

 terious rays. The living leaves were examined by the same method as 

 the extracts, and the diastase in them was found to undergo a similar 

 destruction under the influence of light. 



The experiments lead to the conclusion that there exists in the leaf 

 and in the various extracts examined a certain amount of zymogen, 

 which is converted into active diastase. This conclusion is supported 

 by an extended series of experiments upon the effect of keeping the 

 solutions for several days at the temperature of 38° C. The violet and 

 ultra-violet rays caused the destruction of the diastase, or at least such 

 a change in it that it was unable to affect the hydrolosis of starch. 

 Other conclusions which Avere arrived at by the author are (1) that the 

 enzym is not located in the chlorophyll grain, but in the protoplasm of 

 the cell ; (2) that the suggestion that the red coloring matter of certain 

 leaves is a material help to the translocation of starch in them is prob- 

 ably well founded, as such coloring matters screen off the rays which 

 destroy diastase; (3) that there exists in plants a power of absorbing 

 and utilizing the radiant energy of light without the presence of a 

 chlorophyll apparatus. This last conclusion supplements the observa- 

 tions of Engelmann and Winodgradsky. 



