GERM CELLS OF COELENTERATES 409 
course, be in agreement with those who hold that the chromosomes 
are continuous entities from one generation to the other. But the 
facts do not seem to warrant any such conclusion. 
It can not be claimed that, because some chromatin comes to 
an end different from other chromatin, there is in this very fact 
an indication of its essential unlikeness. Some of the young egg 
cells of Campanularia flexuosa, in moving from the pedicel into 
the body of the gonophore, pass by the only place where there is 
room for them to develop, so they continue their migration (as 
shown in fig. 1) into the distal end of the gonophore, where they 
come to naught but degeneration. Can we say that since this 
egg came to a different end from the one which entered the gono- 
phore where there was more room, it was from the first predeter- 
mined for failure? In other forms—as Tubularia, Pennaria, 
Clava and so forth—it has been clearly shown that two eggs 
have behaved alike for a considerable time, and it is only the 
chance of better position as regards food and room’and the like 
which shall determine which has the opportunity to develop into 
a mature egg and which shall degenerate. 
The chromosomes formed in the manner described in a previ- 
ous paragraph, arrange themselves in a spindle in the usual way. 
They are ten in number, the reduced or haploid number, and 
appear, as figure 19 shows in the metaphase, as single bodies. 
No centrosomes and little indication of polar asters are present in 
the spindle. ‘Two polar bodies are formed (fig. 20 shows one of 
them somewhat degenerate). The spermatozoon appears to enter 
by an attraction cone but leaves no path to indicate its movement 
into the egg. Figure 20 shows the fusion of the two pronuclei 
and the formation of the cleavage spindle. Figure 21 is a section 
through a second cleavage spindle, the right end of which contains 
all the chromosomes, which are seen to be twenty in number; 
the spindle having been cut somewhat obliquely, only a part of 
the chromosomes of the left end of the spindle were present in 
this section. 
Briefly summarizing the nuclear history of the egg cells, we 
find that after the division of one of the epithelial cells of the ento- 
derm of the stem of the gonophore (or by the transformation of a 
single entire cell) the basal half has its chromatin arranged in a 
