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SUMMARY 
• OF CURRENT RESEARCHES RELATING TO 
ZOOLOGY AND BOTANY 
(principally Invertebrata and Cryptogamia ), 
MICROSCOPY, &c., 
INCLUDING ORIGINAL COMMUNICATIONS FROM FELLOWS AND OTHERS/ 
ZOOLOGY. 
A. VERTEBRATA Embryology, Histology, and General, 
a. Embryolog-y.f 
Fecundation. f — M. H. Fol gives an account of his observations on 
the egg of the sea-urchin. The spermatozoon, five minutes after fecun- 
dation, is still conical ; a small corpuscle, the spermocentre, is detached 
from its tip. The spermatic pronucleus then swells and approaches the 
ovarian pronucleus, its spermocentre being always in front. The ovarian 
pronucleus has an ovocentre which is placed on the side opposite to 
that which gives rise to the polar globules. The spermocentre becomes 
placed on the polar side of the ovarian pronucleus, and is afterwards 
applied to its lateral surface. There are now two prolonged phases, the 
“ solar,” and the “ aureolar ” ; at the end of the first of these the 
spermocentre and ovocentre are divided in the form of hal teres, which are 
not placed in the same plane. These halteres become set parallel to one 
another, and are situated in a plane which will be that of the aureole. 
In the next phase the spermocentre and ovocentro become divided and the 
halves, passing in opposite directions along a fourth of the circumfer- 
ence of the combined nucleus, arrive at a point which is at right angles 
to their first position. This M. Fol calls the “ marche du quadrille.” 
At the moment when the demi-spermocentres are on the point of 
touching the demi-ovocentres, the aureole rapidly disappears and true 
asters become apparent ; these are composed of perfectly distinct fibrils, 
which can be isolated and are different from the simple protoplasmic 
radiations visible till then. The demi-centres unite and fuse to form 
the first astrocentres. 
* 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. 
t This section includes not only papers relating to Embryology properly so called, 
but also those dealing with Evolution, Development, and Reproduction, and allied 
subjects. % Comptes Rendus, cxii. (1891) pp 877-9 (10 figs.). 
