44 Papers from the Marine Biological Laboratory at Tortugas. 
34, 56). At the periphery of the egg is a coarsely granular area one or 
several granules in depth (figs. 38, 39). With iron hematoxylin and orange 
G the granules stain deep black like chromatin or yolk granules. They are 
undoubtedly the latter. After a fertilization membrane has been formed 
these peripheral granules have disappeared, nor are they again to be seen 
in the blastomeres of the segmentation stages. It is probable that this 
granular layer contributed to the formation of the fertilization membrane 
and so disappeared when this was fully separated off. If this view is cor- 
rect the fertilization membrane is the egg-membrane thickened by the con- 
tribution from the yolk-granules and as such separated from the ovum. 
Particularly after fixation with sublimate acetic and picro-aceto-sulphuric 
is the close similarity between the cytoplasm in the living and fixed condition 
(but for increased definiteness in the latter case, amounting to an identity) 
very striking. It exhibits a structure of larger and smaller alveoli about 
whose walls are ranged in single line the minute granules or microsomes 
as already described by Wilson and here and there throughout the network 
large granules, probably yolk, similar in size to the peripheral granules. 
The faithfulness of preservation as observed in the cytoreticulum leaves 
little room for doubt that also what is seen in regard to the nuclear retic- 
ulum, the maturation mitoses, and particularly the dissolution of the nucleo- 
lus, are true representations of what actually occurred in the living egg. 
Atypical stages (fig. 56) can, therefore, in no case be regarded as artifacts 
due to faulty fixation, but must be interpreted as the result of abnormal 
development or degeneration processes. 
The living egg shows a nucleus with an extremely delicate meshwork 
spun through a homogeneous ground-substance. Owing to the presence of 
a large amount of nuclear sap, the fixed nucleus differs greatly from that 
of the living egg. The reticulum now appears coarse and wide-meshed 
(figs. 29, 38, 39). It forms a dense basket-work about the nucleolus. 
After staining with iron hematoxylin and orange G, when the hematoxylin 
is greatly withdrawn the reticulum is uniformly yellow; when the stain is 
only slightly extracted chromatic swellings appear along the reticulum, 
giving it a beaded structure, and larger dark-staining masses (karyosomes ) 
are seen at the intersections of the meshes (fig. 39). Auerbach’s stain 
shows no such difference, but leaves the entire network uniformly red. 
Thus again it becomes evident that in the linin of the reticulum are areas 
which in degree of metamorphosis or condensation represent a transition 
stage between linin and chromatin. 
The nucleolus yielded different appearances according to the stains that 
were employed and the length of their application. With the iron hema- 
toxylin and orange G combination the odcyte at the height of the growth- 
period exhibits a nucleolus extremely tenacious of the hematoxylin stain. 
An amount of extraction which renders the cytoplasm and nuclear retic- 
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