ARTIFICIAL PARTHENOGENESIS IN ANNELIDS 671 
on the right side the development of the unfertilized eggs. 
At about the same time a drawing of the fertilized and 
the unfertilized K eggs was made. At 12:45 some of the 
fertilized eggs were found in the four- to eight-cell stage. 
The unfertilized eggs were only amceboid at that time. 
Some of them (see Fig. 158) at 12:55 showed an incision, as 
if they were about to divide. At 1:20 some of the fertilized 
eggs had reached the sixteen-cell stage, and at 1:30 only afew 
eggs were found among the K eggs that seemed to be seg- 
mented. At 2:10 the fertilized eggs were in an advanced 
stage of cell-division, while the K eggs were not distinctly 
segmented. At 3:40 the fertilized eggs had reached the 
trochophore stage, with a clear edge and a dark center. At 
that time the most differentiated eggs of the parthenogenetic 
lot were in the condition that is represented at 3:15 in Fig. 
158. At 4:30 we find these eggs still in the same condition, 
and not until 7:40 did the parthenogenetic eggs reach the 
beginning of the trochophore stage—clear edge and dark 
center (Fig. 158). The fertilized eggs had formed their 
cilia, and at about 5 o’clock were swimming around, while 
the K eggs did not begin to swim until 8 or 9 o’clock. The 
unfertilized control eggs which had remained in normal sea- 
water during this time were at 8 o'clock still absolutely 
spherical, and had given no signs of development or change. 
Although the drawings in Fig. 158 give an idea of the 
development of the parthenogenetic eggs, this idea has to be 
supplemented by the statement that not all the eggs behaved 
like those drawn. The majority of parthenogenetic eggs 
never showed any higher degree of differentiation during 
their development than those drawn in Fig. 157; many eggs 
even remained spherical. The number of trochophores was 
always considerably larger than the number of eggs that 
became amceboid. The majority of parthenogenetic trocho- 
phores are perfectly spherical. I have often wondered 
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