Fig. 1. 
(8) 
Fig. 2. 
(88) 
Fig. 3. 
(9) 
PLATE XXXVII. 
Ctenolabrus from inner surface. Os +% 15 minutes, Merk. 3 days. 2 hours after 32-cell 
stage. 
In the wreath are about twenty-seven cells. Protoplasm radiate around some, no nuclei in 
division. Cap = two to four cells deep; smaller in central, larger in periphery. Round cells 
are seen in the central portion. 
en 1, 2, 3 = delimited. 
en 4 not delimited against pellicle. 
en = syncytial endoderm-cells. 
Endoderm colored red, cap brown. 
For distinction, nuclei of en are red, nuclei of cap brown (Indian red). 
Most of en lie under, not outside, the margin of the cap. In a number of cases the nuclei 
are half under cap, half exposed. [pb = periblast]. 
Two hours after 32-cell [stage]. 42 sections .005 mm. thick. [pb = periblast}. 
The first section cuts edge of cap. Dividing line between marginal cells does not cut quite 
through the periblast. 
The twenty-first section through middle. Marginal cells small, but well colored red, while 
the central cells are all brown. 
The twenty-fourth section shows an inner cell that is reddish, but less so than the marginal 
cell. 
The twenty-seventh section shows no marginal cell. 
The thirtieth section shows red cell above the marginal cell. 
These facts are to be explained by supposing that the marginal cells are constantly dividing 
and adding cells to the cap, which soon after division become like the other cells of the cap, 
taking brown color from osmic acid. 
At this stage the subgerminal plate is pretty complete everywhere. 
It is the upper portions of the marginal cells that are constantly cut off and added to the 
cap, until at length the basal portion ceases to have any connection, and its nuclei spread in 
all directions. 
Ctenolabrus. Two hours after 32-cell stage. [pb = periblast]. A portion of cap from 
above. The endodermal wreath is here very distinct and contrasts with the ectoderm every- 
where in the staining. There are ten pairs of cells and an older one, en'. Three of the pairs 
[en!, en®, en™] are tangential and the rest are oblique or radially placed. In en 1 the division 
is so nearly completed that only the most faint traces of interzonal filaments are discernible. 
The right hand cell of the pair is in plane above ae left, and [is] more sharply defined but 
colored the same. 
en 2 shows last end of division with filaments still visible. A light line between cells indi- 
cates plane of division which is not completed. Both cells continuous with pellicle (pb). 
en 8, [The number does not appear on the plates, but the cells are evidently those between 
en 2 and en 4]. Division completed, inner cell highest, and best defined, but colored lighter 
than rest of ectoderm. 
en 4, inner cell also highest but below the highest of pair en 3. Division completed and 
outline clear in both. 
en 5, same as in 4. 
en 6, both in same plane — faint traces of spindle. 
en 7, division completed. 
en 8, faint spindle-cells not sharply outlined except against the floor-cells of cap. 
en 9, outlined inner cell lighter than ectoderm and appears to be paired with the outer longer 
cell. 
en 10, division not completed, pretty well defined but flowing into pellicle. 
All the inner cells of the pairs, except in en 3, lie in the floor of the cap, and in most cases 
abut against surrounding cells. The paired nature of these cells is most evident. Most of 
the inner cells are covered by ectoderm but wherever they are uncovered, they are colored like 
endoderm. 
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