SUMMARY OF CURRENT RESEARCHES 
RELATING TO 
ZOOLOGY AND BOTANY, 
(principally invertebrata and cryptogamia). 
MICROSCOPY, Etc. 
Including Original Communications from Fellows and Others * 
ZOOLOGY. 
A. VERTEBR AT A Embryology, Histology, and General. 
a . Embryology. f 
Experimental Embryology.^— Prof. G. Born has made experiments 
on the effects of pressure on the segmenting ova of frogs, and his results 
agree in many respects with those of O. Hertwig which were published 
after Born’s communication was written. The compression was either 
parallel to the axis of the ovum or at right angles to it, and in some less 
profitable experiments the ova were compressed in a wedge shaped space. 
In conditions of axial compression, the first two cleavages were normal, 
i. e. there were two meridional cleavages crossing at right angles in 
planes perpendicular to the compressing plates. The third cleavage 
should be horizontal, but instead of this there appeared on the upper 
side of the ova two vertical cleavages, one on each side of the first, and 
more or less parallel to it. The cleavages of the fourth order were 
again vertical, approximately parallel to the plane of the second cleavage. 
In conditions of lateral compression, the first cleavage ran from dark to 
clear pole perpendicular to the direction of the compressing plates. 
There were slight deviations from the perpendicular, as Pfluger observed 
in similar conditions. The second cleavage was always horizontal, and 
again at right angles to the compressing plates, at the boundary between 
the median and upper third of the axis of the ovum. The cleavages of 
the third order began in the two upper small cells, usually as two 
* 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. + Anat. Anzeig., viii. (1893) pp. 609-27 (10 figs.). 
