Bigs 
(71) 
Fig. 2. 
(83) 
Fig. 3. 
(84) 
PLATE XXXV. 
Ctenolabrus. [16-32-cell stage. Somewhat older than stages shown in Plate XXXII, 
Fig. 2]. 9 drawings of a single cap (successive) X 280. [be = blastocoele; pb = periblast]. 
Corresponds to two hours 35 minutes after fecundation. 
The second section has not reached nuclei but has the clear areas. 
Periblast: — The periblast (subgerminal plate) is seen between the cells in the angles formed 
by the adjacent cells. It is quite thick (about .004 mm.). It looks like a thick dense mem- 
brane, is very sharp in outline, and stops abruptly in the angles of the cells. It is thus con- 
tinuous with the lower surface of the cells. There is a strong contrast between it and the 
protoplasm. The latter is granular but the periblast is more homogeneous and membrane like. 
It is quite as strongly stained with carmine as the protoplasm. Very small open triangular 
spaces are seen above the periblastic parts. 
The third section shows larger spaces in angles of cells and reveals more extensive position 
of periblast. One pole of three nuclei is seen. The periblast is a little less thick. 
The fourth section shoys the other poles of two [of these three] cells. The periblast terminates 
in the angles of two peripheral cells, and is entirely free from the central ones, except perhaps the 
right central, under which no distinct membrane can be seen but a light colored substance 
extends beneath this cell connecting the periblast. The periblast would seem to form by growth 
from the superficial yolk. This explains why it is often wanting near the center of floor, and 
often appears continuous with a superficial lighter colored layer of the yolk, as seen in section 
eight. 
The eighth section cuts two marginal and two central cells. (The four central cells are blacker 
than the marginal ones as was seen both before and after sectioning). Here the plane of division 
is marked. In the central cells observe the inclination. Notice the nuclei; they are in edge of 
light areas, and a poorly defined small area, about size of nucleus or a little larger, is seen in 
each case on the outer pole of the nucleus. 
The periblast is much thinner, becomes less dense, lighter, and poorly defined under central 
cells. Yolk [is indicated] below these cells to show that the forming periblast merges into it. 
The ninth section = same cells. 
The tenth section = right cell, at middle, in passing to next cell. 
The twelfth section corresponds to section eight. 
The nineteenth section corresponds to section four. 
The periblast forms a continuous sheet in sections seventeen, eighteen, and nineteen, but is 
interrupted in the twentieth. It is very thin centrally in section seventeen, plainer in eighteen, 
plainest in nineteen. 
32-cell [stage section; bc = blastocoele]. The central cells are browned more than the 
marginal, the marginal are redder than the central. 
The interesting fact is that the lower central cells are also more brown, just like the upper 
central cells, thus appearing to have the same value. 
Transverse section, near middle [pb = periblast]. On the right [lower end of figure] is 
seen a nucleus in the periblastic swelling or rim. Perenyi swells the material a little and renders 
it easier to trace the periblast. The periblast stretches across in a very thin evanescent layer. 
Along the middle, it is not seen, except between two cells, where it appears to be continuous 
with them. Cap two layers deep in central part, but these central cells are all browner than 
the marginal in eggs treated with osmic and Merkel. 
