160 Scientific Proceedings^ Royal Dublin Society. 



others the intensities and distribution of the oxydase reactions appeared to 

 be identical. On the whole, it may be said that leaves from the dark contain 

 the inhibitor in the lower half of the leaf, while those in the light have a 

 more widespread distribution. It is, however, by no means certain that this 

 is not due to individual variations or to the weakened condition of the plants 

 in the dark. 



(J) The Flowers of Iris. 



A number of species and forms were obtained during June and July, 

 1913, from the Botanic Gardens of Trinity College, Dublin. Care was taken 

 to verify the garden names as far as possible. For this purpose Lynch's 

 Handbook (9) and Dykes' Monograph (3) were consulted, as well as the 

 specimens in the Trinity College Herbarium. I am, moreover, much 

 indebted to Mr. "Wild, of the Botanic Gardens, for assistance in identifi- 

 cation. 



Adopting the usual nomenclature, the outer drooping perianth leaves are 

 termed the "falls," the usually erect inner three being known as "standards." 

 Of these the lower part is the " haft " and the upper the " blade." Owing to 

 the fact that the falls, which are opposite the stamens, are usually of a greater 

 diversity of colour than the standards, the former have been employed in the 

 majority of the tests. 



Members of three large groups have been utilized, namely, the Xiphion, 

 the Pogoniris, and the Apogon groups. The last is very large, and includes 

 such different forms as the yellow flag Iris 1. pseudaconis, the large 

 Japanese /. Kaempferi, and the small-flowered /. sibirica. The members of 

 this group seem to be less closely connected with each other than are those of 

 others, and crosses are often sterile. The Pogoniris group contains 

 those flowers which have a beard of multicellular hairs on the hafts 

 of the falls, such as /. gevmanica and the sweet-scented /. pallida. The 

 Xiphion group is usually well represented by the many garden forms of 

 Spanish Iris, /. Xiphimn, and of English Iris, I. ccij^lnoides. 



In Table I are recorded the results of the application of the various 

 reagents to /. xiphioides. The first column is for the restoration of the 

 natural colours by immersion of the leaf in water ; these had previously 

 been destroyed by soaking in strong spirit till colourless. Both processes 

 were at air-temperature, and one day was allowed for the restoration, but 

 several observations were made during that period. The other columns 

 show the character of the reactions with benzidine and a-naphthol, hydrogen 

 peroxide being added in each case to the extent of five drops of a neutral 

 four- volume solution to each petri dish containing the specimens. It should 



