ARTIFICIAL PARTHENOGENESIS IN ANNELIDS 673 
two spheres fused, and a small sphere or droplet appeared 
above (8:054). This disappeared almost immediately, and a 
new little droplet broke loose at the right lower side of the 
egg (8:06). It disappeared in a few seconds, and the egg 
once more divided, but with an altogether different position 
of the cleavage plane (8:064, 8:074). In a few seconds 
the two spheres fused into one cell, and 
a number of small droplets appeared 
below (8:08). Of course it is impos- 7 77 
sible to tell whether or not these single 
spheres or droplets contained nuclei. 
These phenomena are of importance for 
the mechanics of development, inasmuch as they show that the 
bulk of the egg is liquid, and that in the case of Cheetopterus 
its viscosity is very small, and less than in the case of the 
sea-urchin’s egg. It is hard to understand what kind of 
structure could be preformed in a liquid mass of such low 
degree of viscosity beyond the differentiation into nuclear 
and protoplasmic material and possibly centrosomes. 
The appearance of the trochophores originating from un- 
fertilized eggs is exactly like that of those arising from fer- 
tilized eggs, if one compares equal stages of development. 
Fig. 158 gives no good idea of the trochophore, inasmuca 
as the latter is at first spherical. Fig. 160 shows two 
parthenogenetic trochophores, drawn by the camera with 
the exception of the cilia, which are more or less diagram- 
matic. The eggs from which these trochophores originated 
had been treated with KCl. It is hardly necessary to men- 
tion that the appearance of the trochophores developing 
from parthenogenetic eggs depends greatly upon the treat- 
ment the egg had received. I mentioned this point in 
connection with the artificial parthenogenesis of sea-urchins. 
A point which must be discussed is the duration of 
life of the parthenogenetic trochophores. All the Che- 
FIG. 160 
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