SUMMARY OF CURRENT RESEARCHES 
RELATING TO 
ZOOLOGY AND BOTANY 
(principally invertebrata and cryptogamia), 
MICROSCOPY, Etc. 
Including Original Communications from Fellows and Others .* 
ZOOLOGY. 
A. VERTEBRATA : — Embryology, Histology, and General. 
a . Embryology. f 
Experimental Embryology. — Prof. O. Hertwig i has made fresh 
experiments on the influence of external conditions on the development 
of the ova of the frog ( Bana fusca). The maximum temperature at 
which the ova will develope normally (though more rapidly than usual) 
is 25° C. Higher temperatures affect the ova injuriously, particularly 
the vegetative part, and partial forms occurred like those which Roux 
produced by his puncturing method. The animal half is the hardier, 
for it has relatively more protoplasm, and that is more thoroughly under 
nuclear influence. Lowering the temperature inhibits development, just 
as an increase accelerates it. 
Prof. Hertwig has also experimented on the influence of salt -solutions, 
as Morgan and CJme Tsuda have done. With solutions of 3 : 500 the 
formation of the blastopore and the development of the brain were 
especially affected. The invagination forming the archenteron was 
restricted to a small portion at the margin of the yolk-area, very much 
as in meroblastic discoidal segmentation. As regards the brain, the 
abnormality induced was comparable to hemicephalous and anen- 
cephalous conditions in human teratology, a resemblance on which the 
author comments. 
* 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 Embryolgy properly so called, 
but also those dealing with Evolutioh, Development and Reproduction, and allied 
subjects. % SB. K. Preuss. Akad., 1894, pp, 311-7. 
