370 Proceedings of Boy cil Society of Edinburgh, [july 15 , 
system and the vertebral plates in chick embryos of forty to forty- 
eight hours forms a thin membrane. On nearing the ventral portion 
of the vertebral plates the epiblast becomes slightly thickened, while 
immediately beyond the vertebral plates there is a slight involu- 
tion and a considerable thickening in the outer layer. On passing 
to the lateral mesoblast the epiblast again thins out. Here, evi- 
dently, is an epiblastic thickening corresponding precisely in position 
with that forming the segmental duct in other vertebrates. In the 
chick, however, the “ intermediate cell mass ” is comparatively large, 
and the epiblastic thickening soon becomes fused with the meso- 
blast. In a forty-eight hour chick embryo I have noticed a curved 
line more distinctly shown in some sections than in others, which 
I take to define the limit of the epiblast. In the posterior portion 
of the embryo the epiblast and “ intermediate cell mass ” are quite 
separate, and I was unable to trace any thickening in the epiblast 
of that region. Probably, therefore, the duct is pushed backwards 
from the anterior portion without coming into contact with the 
epiblast. This, at any rate, is the mode of development previously 
described in Elasmobranchs and birds, when the segmental duct was 
supposed to have a mesoblastic origin. 
The whole of these recent researches must necessarily lead to a 
modification in our views of the morphology of the vertebrate 
excretory apparatus. Haddon has recently suggested that primi- 
tively the nephridia (derived from the mesoblast) opened on each 
side into a lateral groove, that later this groove deepened and 
formed a closed canal, which subsequently acquired a secondary 
opening to the exterior through the cloaca. 
I propose to discuss this subject more fully in a future paper. 
3. Preliminary Note on the Chemistry of Strophanthin. 
By Thomas It. Fraser, M.D., F.P.S., Professor of Materia 
Medica in the University of Edinburgh. 
Since my former communications, in which several facts relating 
to the chemistry of Strophanthus hispidus have been stated, I have 
completed a systematic examination of various parts of this plant, 
and more particularly of the seeds. Eeserving a detailed descrip- 
