SUMMARY OF CURRENT RESEARCHES 
RELATING TO 
ZOOLOGY AND BOTANY 
(principally invertebrata and cryptogamia), 
MICROSCOPY, Etc. 
Including Original Communications from Fellows and Others .* 
ZOOLOGY. 
VERTEBRATA. 
a . Embryology.! 
General Embryology.! — Dr. R. S. Bergb has published a series of 
lectures on general embryology. The first four deal with conjugation, 
sex-cells, and fertilisation. The others discuss segmentation, the ger- 
minal layers, organogenesis, experimental embryology, regeneration, 
alternation of generations, and the like. There are two interesting his- 
torical chapters on fertilisation and on embryology in general ; and the 
work concludes with some practical directions to students. Dr. Bergh’s 
lectures are terse and lucid, and are illustrated by some very instructive 
diagrams. 
Experimental Embryology.§ — Prof. 0. Hertwig gives a short ac- 
count of his experiments on the influence of varied temperature on the 
development of frog ova. By a simple but effective contrivance he 
arranged a series of basins with a constant flow of water at temperatures 
from 15°-35° C., and with fluctuations of only • 1° C. For lower tem- 
peratures (0° — 10°) the fluctuations were greater, about 2° in a day. 
(1) In water at 0°, fertilised eggs did not develope at all, and developing 
eggs ceased to make further progress. But even after weeks at 0° eggs 
may develope normally if gradually warmed. (2) Normal development 
of frog ova may occur between 2° and 33° C. This is markedly con- 
trasted with the narrow limits of possibility in the case of the hen’s egg. 
(3) There are slight differences between the limits for liana fusca and 
* 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. 
+ ‘ Vorlesungen fiber allgemeine Embryologie,’ Wiesbaden, 1895, 8vo, x. and 
289 pp., 126 figs. § SB. K. Preuss. Akad., 1896, pp. 105-8. 
1896 2 t 
