May 31, 1901.] 
some measure a direct and independent func- 
tion. 
R. 8: WooDWoRTH, 
Secretary. 
SECTION OF BIOLOGY OF THE NEW YORK ACAD- 
‘ EMY OF SCIENCES. 
A REGULAR meeting of the Section was held 
on April 8th, Mr. M. A. Bigelow presiding. 
The following program was offered : 
E. B. Wilson: ‘The History of the Centrosomes in 
Artificial Parthenogenesis, and its Relation to the 
Phenomena of Normal Fertilization.’ 
F. S. Lee: ‘Some Observations on Rigor Mortis.’ 
In continuation of his communication given 
at the December meeting, Professor E. B. Wil- 
son presented the results of further studies on 
the development of the unfertilized eggs of 
Toxopneustes when treated by Loeb’s magne- 
sium chloride method. The principal points 
considered were the origin and history of the 
centrosomes and the general relation of the 
phenomena to those occurring in normal fertili- 
zation. Evidence was brought forward that 
the cleavage centrosomes of the primary divi- 
sion figure arise by the division of a single 
primary centrosome that is formed outside, but 
immediately upon, the nuclear membrane. 
As regards the chromatic transformation of the 
nucleus, two types of chromosome formation 
were described. In both cases a large nucleo- 
lus is formed, which attains a much greater 
size than in the fertilized eggs. In one type 
this nucleolus remains a plasmosome, or true 
nucleolus, which fades away at the time of 
division, the chromosomes arising nearly in the 
usual manner from the chromatin network. 
In the second type, the entire chromatic con- 
tent of the nucleus is gradually accumulated 
in the nucleolus, which thus forms a chromatin- 
nucleolus, from which the chromosomes are aft- 
erwards derived nearly in the same manner as 
in Spirogyra. In regard to the accessory asters, 
or cytasters, it was shown that they contain 
central bodies often indistinguishable in sec- 
tions from the centrosome of the nuclear fig- 
ure, though in many cases less well devel- 
oped. Sections demonstrate that the division 
of the cytastersis preceded by division of 
the central body, which draws out to form a 
SCIENCE. 
865 
central spindle in a manner similar to that de- 
scribed by MacFarland in the eggs of gastero- 
pods. This fact, taken in connection with the 
physiological activities of the cytasters, seems 
to remove every doubt regarding the identifi- 
cation of the central bodies as true centrosomes. 
In comparing the phenomena in the magnesium 
eggs with those of normal fertilization, it was 
pointed out that the formation of accessory 
asters at the time of fertilization or cell-divi- 
sion is a widespread phenomenon. In normal 
fertilization or division, the accessory asters 
are of very transient character. In the mag- 
nesium eggs they attain a much greater devel- 
opment both structurally and functionally, 
but they are probably to be regarded as differ- 
ing only in degree from those which appear 
during the normal process. In all cases, their 
disappearance is probably due to a concentra- 
tion of the protoplasmic activities about the 
more active centers, connected with the nu- 
cleus, which alone survive to perform the nor- 
mal functions of division. Evidence was ad- 
duced that the nuclear transformation oceurring 
in normal fertilization is not primarily due to 
the union of the sperm-nucleus, or sperm-cen- 
trosome with the egg-nucleus, but to a general 
stimulus of the ovum effected by the entrance 
of the spermatozoon. Apart from the different 
character of the stimulus, this transformation 
of the egg-nucleus does not differ essentially 
from that taking place in the magnesium eggs. 
This is proved by the fact that in etherized 
eggs the egg-nucleus may undergo the karyo- 
kinetic transformation without union with the 
sperm-nucleus or centrosome —an observation 
which agrees with the much earlier results of 
O. and R. Hertwig on eggs treated with chloral 
hydrate. In normal fertilization this activity 
of the egg-nucleus is modified through its 
union with an active individualized sperm- 
centrosome, the presence of which inhibits the 
formation of an egg-centrosome such as occurs 
in the magnesium eggs. 
Professor F. 8. Lee stated that rigor mortis 
is characterized by a shortening of the muscles 
of the body, accompanied by a coagulation of 
the contents of the muscle cells. The nature 
of the phenomenon is disputed. Hermann has 
long insisted that it is analogous to muscular 
