A Comparative Study of the Structure and Origin of the Yolk Nucleus. 679 
It is easily seen, also, that in the surrounding cytoplasm, there is a 
regulär, radial arrangement of the fibers; that thcse proceed front the 
center; and in fact, form an aster, the rays of which are continuous with 
the cytoreticidum. It is, therefore, a typical centrospherc, vcry similar 
to that seen in figs. 64, 68, 71 and fig. 74. Nothing but preconceived 
ideas regarding the origin of the centrosome de novo, — a claim which 
has not yet been proven — would prevent us front inferring that this body 
originates from the centrosome of the dividing oogonia. It has all the 
characteristics of a true centrospherc. It maintains tliese characteristics, 
(tliough often ntuch ntodified by accumiüating yolk gramdes), in later 
stages of growth of the egg, figs. 26, 27, 32, 39, 40—63, 67, 70, 73. 
In fig. 42, the body is shown as it appears in an egg about one half 
the size of the fully maturcd egg. It is drawn with low magnification; 
and it is a true picture of what everyone can see for himself in my 
preparation. 
The section of an egg represented in fig. 46 is drawn with a higher 
magnifying power. It is a platinum chloride preparation, beautifully 
preserved. It shows a large body in the center of the cytoplasm con- 
nected with the germinal vesicle in the same way as is the similar body 
in the egg of the tortoise, pl. XXIX. The zoncs are distinetly separated as 
if by a membrane ; and the radial fibers within the body, are exceedingly 
fine and dosely arranged, giving a silken effect. Stained with the 
Biondi-Erlich mixture, its color is a golden brown, wliile the rest of 
the cytoplasm is reddish. 
Taking the forms mentioned as the typical forms most clearly sug- 
gesting the centrosphere, it is possible to understand the many other 
Strange forms met with in these eggs. The body represented in fig. 31 
appears as a blidsh grcen body from Lyons blue, the rest of the egg show- 
ing the red of saffranin. It contains vacuoles with dark granules re- 
sembling nuclei. 
In fig. 34 is represented a vitelline body like that of spiders. A 
distinct astral arrangement of the fibers is visible around the main portion, 
which Stands out large and conspieuous. 
Very often the central, tangled mass of fibers, enclosing one or several 
granulär vacuoles, is surrounded by a zone of large blue granules. These 
are seen most clearly in material stained with hematoxylin, fig. 37 ; but 
also in other stains, as acid fuchsin, fig. 33. 
As in the spider, the central felted mass consists of very fine fibers 
enclosing minute meshes, which sometimes form large vacuoles, fig. 35. 
The minute fibers and meshes pass imperceptibly into the general cyto- 
