SUMMARY OF CURRENT RESEARCHES 
RELATING TO 
ZOOLOGY AND BOTANY 
(principally invertebrata and cryptogamia). 
MICROSCOPY, Etc.* 
ZOOLOGY. 
VERTEBRATA. 
a. Embryology, f 
Development of Sphenodon. — Prof. Arthur DendyJ has obtained ex- 
tensive series of developing eggs of the Tuatara from Stephens Island, 
and has been able to investigate the development in some detail. The 
eggs are laid in special holes carefully excavated in the surface soil and 
subsequently closed with grass and leaves. They seem to take about 
thirteen months to develop, and are laid in November. 
The blastoderm spreads round the yolk very rapidly, and the seg- 
mentation cavity is large. The mesoblast arises in part from the 
primitive streak, in part from cells left between epiblast and hypoblast 
after the differentiation of the latter. The proamnion originates before 
the differentiation of hypoblast, so that its first rudiment consists not of 
epiblast and hypoblast, but of epiblast and undifferentiated lower layer. 
Owing to the extent to which the head of the embryo sinks down into 
the yolk, the proamnion is a very conspicuous structure, and persists 
till a comparatively late stage of development, its presence modifying the 
shape of certain of the organs. As in Chelonians, there is a distinct 
posterior amniotic canal. The allantois reaches a great size, its cavity 
being much greater than that of the amnion. The parietal eye arises 
from the primary parietal vesicle which originates slightly to the left 
side of the dorsal surface of the fore-brain. The “ stalk ” of the parietal 
eye is probably the right parietal eye retarded in development. In 
the development of the olfactory organs, a remarkable circumstance 
is the plugging up of the nostrils with a dense mass of cells. This takes 
place just before the beginning of the long winter rest, but the sugges- 
tion that it has anything to do with the hibernation seems to be negatived 
by the fact that a similar process was described by Parker in the embryo 
* The Society are not intended to be denoted by the editorial “we,” and they do 
not hold themselves responsible for the views of the authors of the papers noted, 
nor for any claim to novelty or otherwise made by them. The object of this part of 
the Journal is to present a summary of the papers as actually published , and to 
describe and illustrate Instruments, Apparatus, &c., which are either new or have 
not been previously described in this country. 
f This section includes not only papers relating to Embryology properly so called, 
but also those dealing: with Evolution, Development and Reproduction, and allied 
subjects. X Quart. Journ. Micr. Sci., xlii. (1899) pp. 1-87 (10 pis.). 
1899 t 
