324 



Scientific Proceedings, Royal Dublin Society. 



found by tlie writer that tlie leaves of /. germaitica showed no change in 

 peroxidase reactions when deprived of liglit. This, however, is a relatively 

 massive tissue when compared with the blade of a floral leaf. 



With a view to testing the above possibility the Irises mentioned in 

 Table VI were picked at 5 p.m. on July 10, 1914, after a hot, snuny day. Of 

 each flower one of tlie falls was removed and examined immediately. The 

 reactions afforded by these are given in column No. I. The flowers were then 

 placed in total darkness, with their stalks in water. After twenty-one hours 

 the second of tlie falls was removed, and the third after sixty-six hours. 

 The beliaviour of these is shown in Nos. II and III respectively. In tlie 

 table + refers to the whole of the fall, unless a portion such as the claw is 

 mentioned. Thus, "+ claw" indicates a less general distribution than does 

 + alone. The reagent employed was a-naplithol, as it is more selective in its 

 action than is benzidine. 



Table YI. 



Effect of keeping in darkness upon the peroxidase reactions of Iris flowers. 



' These gave a colour without the addition of hydrogen peroxide, and so contained organic 

 peroxide. 



