318 



Scientific Proceedings, Royal Dublin Society. 



leaves of tlie above-mentioned /. pseudacorus, of I. Xiptiium, I. xiphiodes, 

 and /. pumila, all failed to turn guaiaeum tincture blue. On testing the tips 

 of the leaves separately it was only in /. pumila that an active peroxidase was 

 detected. The blue colour it produced was quickly destroyed when a fragment 

 of the lower portion of the same leaf was added to the solution. 



The following tables record the behaviour of the various groups of 

 Iris : — 



Table I. 



Apogon Group. 



a-Naphthol 



I. mujxiicularis, Poir., muture flower, 



/. ungitieularis, bud, blue colour slightly deeper, 



1. ungitieularis, mature, ..... 



/. tinquicularis, blue colour slightly deeper, bud 



just opening, 

 /. unguiouliiris, young bud, colour deeper still, . 



/. tingideularis alba, ..... 



Ditto, 



I. unguiotliiris var., ..... 



Ditto 



/. tmguicularis speciona, . ... 



Ditto, 



Ditto, unopened bud, . . ' . 



Veins 

 + + 



+ + 



+ + 



+ + 

 + 



+ + 



+ + 



+ + 



Epiderir 



+ + 



+ + 

 + + 



slight 



Veins 



+ + 



+ + 



+ + 



+ + 



+ + 



+ 



gbt 

 + 

 gbt 



slight 



_+ 

 slight 



Epidermis 



+ + 



+ + 



+ + 



Discussion of Results of Table I. 



The similarity of the reactions of the buds and mature flowers in the 

 different varieties of this Iris are clearly shown in the table. It will be 

 noticed that here, as usual, the a-naphthol reaction is more sensitive to the 

 inhibitor than is the benzidine. 



It seems worthy of mention that the first five were examined on 

 February 6. These give pronounced reactions. The remaining seven were 

 tested on February 19, and the a-naphthol reactions were feeble, or negative. 

 It is possible that this may have been due to differences in illumination. The 

 question will be discussed later on. 



' This denotes the absence of any reaction. 



