THE RECENT BALTIMORE MEETINGS OF SCIENTIFIC 
SOCIETIES 
ZOOLOGY 
Both the American Society of Zoologists and Section F 
(Zoology) of the American Association held meetings. Thirty 
three papers were read before section F and fifty nine papers 
before the Society of Zoologists. The meeting like all those of 
recent years in America gave ample evidence of the strength of 
the analytic tendency. Striking discoveries in morphology whether 
of adult forms, larvae, or embryos, or of tissues, or of cell group- 
ings and movements during embryonic life, continue to be few. 
The relationships of animals (phylogenetic classification) have for 
the time being almost dropped from the list of subjects discussed. 
Keen interest is however manifested in morphological data that 
can be interpreted as throwing light on the physiology of develop- 
ment. Prominent in this connection were papers by E. B. Wil- 
son and T. H. Morgan on sex determination and the nuclear con- 
stitution of the sperm in certain insects. These investigators 
produced new facts as to chromosome arrangement w T hich lend 
support to the hypothesis that sex is determined in the individual 
germ cell by the presence of a male-producing or female-produc- 
ing chromosome. 
Underlying this special question of sex determination is the 
general question as to the nature of the whole process of differen- 
tiation during development. As bearing upon this question E. 
G. Conklin presented the results of an experimental study of egg 
organization in ascidians and mollusks. Earlier studies led him 
to the conclusion that the egg cytoplasm in these forms becomes 
differentiated into substances (“organ -forming substances”) that 
have fixed and different potentialities, such for instance as a cyto- 
plasmic area that necessarily develops into the notochord. 
Conklin employing the centrifuge alters the arrangement of sub- 
148 
[December 
