PHYSIOLOGICAL EFrrects or Lack oF OxyGEN 885 
of the peripheral cell-limits had already become invisible 
(Fig. 106), and after another fifteen minutes nothing could 
be recognized of the entire blastoderm except a collection of 
droplets which had fused into larger drops (Fig. 107). In 
the next two hours the latter only became more spherical, 
but otherwise under- 
went no change (Fig. 
108). The germdisk 
was optically still less 
visible than in the 
unfertilized egg. It 
therefore required 
only thirty-five min- 
FIG. 103 utes after cleavage 
came to a stop, for 
the complete liquefaction of the cleavage-cells of an eight- 
celled blastoderm. It is scarcely necessary to mention that 
the same process in various experiments took a little more or 
a little less time. 
FIG. 104 
What we observe here is found in every 
such experiment upon Ctenolabrus eggs, the 
only difference being 
in the form and the 
arrangement of the 
droplets of the 
strongly refractive 
material, which at 
times may form a 
more perfect cast of 
the old lines of cleavage than in the experiment described. 
Even when the oxygen is driven out so slowly that the egg 
has time to reach the sixteen- or the thirty-two-cell stage in 
the stream of hydrogen, the same series of degenerative 
changes occurs as soon as cleavage has come to a standstill. 
FIG, 105 FIG. 106 
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