SUMMARY OF CURRENT RESEARCHES 
RELATING TO 
ZOOLOGY AND BOTANY 
(principally invertebrata and oryptogamia), 
MICROSCOPY, Etc. 
Including Original Communications from Fellows and Others .* * * § 
ZOOLOGY. 
VERTEBRATA, 
a. Embryology.! 
Determination of Sex4 — Heir L. Cohn lias collected the facts and 
theories on this subject. As is well known, there are too few facts to 
warrant any general theory. It seems certain that the sex of the off- 
spring may be affected by numerous factors. Schenk’s theory is con- 
demned as a hypothesis based on very insufficient evidence. Schenk 
gives only three or four cases which bear out his theory. Cohn is at 
least more cautious. 
Telegony.§— Hr. Otto vom Rath discusses the possibility of coin- 
foetation in mammals in its bearing on this subject. Certain breeding 
experiments of his own, and of Herr Fr. Engelmann’s in the case of 
dogs, convince him that it does occur, though he admits the difficulty 
of eliminating the possibility of reversion in the case of the more 
specialised breeds. He explains the phenomenon as the result of the 
fact that, in the case of animals which bring forth many young at a 
birth, the eggs are not all ripe simultaneously, but may be shed into the 
oviduct at intervals of several days, and so be fertilised at different 
periods. He believes that the appearance of badly bred pups in a 
litter, which breeders regard as the result of telegony, may be accounted 
for in this way. He is not able to believe in the possibility of telegony 
on the evidence as at present stated. 
* 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 ealleJ, 
but also those dealing with Evolution, Development, and Reproduction, and allied 
subjects. 
X ‘Die willkiirliche Bestimmung des Geschlechts,’ Wurzburg, 1898. See Biol. 
Centralbh, xviii. (1898) pp. 589-90. 
§ Biol. Centralbl., xviii. (1898) pp. 637-42. 
