19^3- Irish Societies. 
DUBLIN MICROSCOPICAL CLUB. 
December ii. The Club met at Leinster House, The President 
(J. H. Woochv'orth) in the chair. 
C. F. Ball showed photographs of a new epiphytal orciiid called 
Angyaecum Andcrsonli, a native of the Gold Coast, West Africa. It has 
a short stem three inches long, which grows downwards, and from which 
hang roots eighteen inches in length. The stem bears small flowers of 
an almost transparent white with green stripes on the sepals, and a green 
column. The special interest attached to this orchid is that it is leafless, 
the aerial roots doing the work of attachment, absorption, and assimi- 
lation of food. A section of the root showed the cortical cells full of 
chlorophyll, a thin velamen for absorption of moisture, and strong root 
hairs which serve for attachment. 
F. W. Moore showed portion of the leaf of a hybrid Sedum, obtained 
ffom the late William Corderoy. The leaves were covered with large uni- 
cellular glandular hairs which secreted from the apex a drop of clear 
glutinous fluid. These glandular hairs formed very interesting objects 
when examined under a low power. 
W. F. GuNN showed scales from the underside of the leaf of Elcagniis 
japoniciiF. Thi.^ plant, which is a native of China and Japan, grows 
naturally in dry positions, so that it is desirable to limit the amount of 
transpiration through the leaves. The scales, which are very closely set 
on the lower surface of the leaves where the stomata are numerous, help 
materially to do this. Under ordinary light the scales are quite trans- 
parent and featureless, b'.it the use of polarized light enables the structure 
to be seen much more distinctly, and the use of a selenite disc greatly 
intensifies the colours. 
N. CoLGAN exhibited a series of slides illustrating the microscopic 
structure of the replum or false dissepiment in the Cruciferae. An ex- 
amination of some forty-five species of European crucifers appeared 
to the exliibitor (whose researches in this direction are as yet incomplete) 
to justify the conclusion that a generic character is afforded by the varied 
patterns formed by the system of fibres traversing the replum. In the 
genus Alyssum, of which seven distinct species had been examined, the 
constancy of type in this pattern was shown to be specially well marked. 
In other genera, too, e.g., Arabis, Cardamine, Draba, Lepidium, Cochlearia, 
Thlaspi, Diplotaxis and Brassica, of which a lesser number of species 
had been examined, ranging from five in Arabis and four in Cardamine, 
to three each in the remaining six genera, this constancy of type was found 
to obtain. The variety in the form and disposition of the fibres traversing 
the replum in the species so far investigated, renders it not improbable 
that a specific character for each of the numerous species of Cruciferae 
provided with a replum may be found in the microscopic lineation of 
that portion of the fruit. It remains to be seen whether a classification 
of the Cruciferae, founded on such a character, would run parallel with 
existing classifications drawn from more obvious distinctive marks. 
Indications of the existence of such a parallelism are not wanting. It 
