244, W. WALDEYER. 
that the mass of male and female chromatin is unequal, whilst 
in Ascaris, as already stated, a perfect equality exists. 
Carnoy (I. c.) stands, so to speak, midway between the 
followers and opponents of E. van Beneden. 
In his two works, ‘ La vésicule germinative et les globules 
polaires de l’Ascaris megalocephala, and ‘La vésicule 
germinative et les globules polaires chez quelques nématodes,’ 
vide the journal published by him, ‘La Cellule,’ t. ii and in, 
1886, he comes to the conclusion that in many cases a fusion 
gives rise to a segmentation-nucleus in O. Hertwig’s sense ; 
but in many cases this is not so, and in these cases segmenta- 
tion commences before a conjugation of the pronuclei occurs. 
If this were so, the fusion would have no special significance. 
Nussbaum (148) and O. Zacharias (210) strongly support fusion 
as aregular occurrence. Zacharias, who has followed minutely 
the process of fertilization in Ascaris megalocephala 
since E. van Beneden and Carnoy, believes that van Beneden 
has overlooked the stage of fusion. Two examples in this 
species are discussed. In the first case two chromatin sphe- 
rules remained after the extrusion of the directive corpuscles 
from the chromatophilous substance of the germinal vesicle ; 
the intrusive spermatozoon exhibited just such another couple 
of spherules, and so far E. van Beneden’s account was con- 
firmed. Now, however, a male and female spherule united to 
form a nuclear-like structure, after forming a membrane round 
themselves. This divided up into a great number of micro- 
somes, which became mingled with one another and gathered 
up into a thread-skein, so that it was impossible to distinguish 
therein the male and female elements. Obviously these two 
nuclear-like structures thus transformed are van Beneden’s 
two pronuclei. When, later on, the first segmentation occurs, 
there is no further fusion of the chromatin thread-skeins of 
these two pronuclei. ‘The nuclear membrane around each 
chromatic skein disappears. Hach skein divides up into two 
V-shaped loops, each of which then splits longitudinally to form 
two sister-threads. The eight loops, now present, arrange them- 
selves as a mother-star around the spindle figure which has 
