1056 The American Naturalist. [December, 
EMBRYOLOGY: 
Fertilization.—Our present conceptions of the meaning and of the 
cell factors concerned in the act of fertilization have been based so 
largely upon the views of Boveri and these arose so directly from the 
study of the eggs of Ascaris megalocephala that it is of the greatest im- 
portance to know how far we rest assured in the knowledge of the truth 
in this classical object. 
The well-known editor of La CELLULE has with M. H. Labrun re- 
studied fertilization in this worm and obtained facts quite at variance 
with those commonly accepted. Professor Carnoy studies sections that 
are obtained after killing the eggs with a mixture of absolute alcohol, 
chloroform and acetic acid saturated with corrosive sublimate and this 
certainly yields most beautiful pictures of reticular appearances 
throughout cell and nucleus. 
While Boveri regarded the introduction of a centrosome by the sperm 
as a most important part of fertilization Carnoy denies that there is any 
such fact. For Boveri, the sexes are not alike since the egg has no 
centrosome to start the process of fertilization and the sperm has such 
a centre. For Carnoy, there is entire equality of the sexes since both 
sperm and egg each furnish a centrosome for the first cleavage and in 
every other way the fertilized egg is a combination of the same elements 
from both sexes. 
A cardinal point in Carnoy’s observations is the fact, as claimed, 
that the nucleoli pass out from the nuclei and become the centrosomes ! 
The centrosomes also vanish after each cleavage and do not divide to 
make new ones! 
A summarization of his facts includes the following assertions: 1. 
At the last division of the series of cells that form eggs, the centrosome 
vanishes from the protoplasm and new ones are formed in the nucleus 
of the unripe egg. 2. In the formation of the polar bodies these cen- 
trosomes emerge from the nucleus and function; perhaps they disap- 
pear after the first, and are formed again for the second, polar body. 3. 
Both polar bodies are formed with the presence of centrosome and 
asters; but these structures then disappear and there is no centre left. 
in the protoplasm of -the ripe egg. 4. The sperm introduces a large | 
mass of reticulum and this acts upon the reticulum of the egg to pro- 
1! Edited by E. A. Andrews, Baltimore, Md., to whom abstracts, reviews and 
reliminary notes may be sent. 
