330 PROCEEDINGS OF THE ACADEMY OF [April, 
MATURATION AND FERTILIZATION. 
It is not the purpose of this paper to discuss in detail the maturation 
processes of the egg, but a few words in that connection may not be 
amiss. Maturation appears to have begun at the time of laying, since 
the first polar spindle is already formed in all eggs examined. In 
fig. 1 the chromosomes have moved to opposite ends of the first matu- 
ration spindle, and at a slightly later period, fig. 2, the sperm may be 
seen making its way through the yolk globules toward the upper pole. 
In a large number of sections examined the sperm is seen to have 
entered at some point below the equator of the egg, though apparently 
never directly at the center of the vegetative pole. The chromatin 
of the sperm nucleus is but slightly evident at this time, but astral 
radiations are strongly marked in the surrounding cytoplasm. The 
clear more protoplasmic substance of the egg becomes aggregated 
principally around the first polar spindle and in the neighborhood of 
the sperm nucleus, though long strands of finely granular protoplasm 
extend through nearly the entire egg, forming the astral rays. The 
yolk, which is in the form of rather small yolk globules, encroaches 
closely upon these centers, but is not, as a rule, found within them. 
As the first polar body arises, the upper surface of the egg becomes 
distinctly indented immediately above the first polar spindle and from 
this depression the first polar body emerges, bearing with it the distal 
end of the first maturation spindle, which rises as a whole toward the 
upper surface of the egg. During this process the sperm nucleus and 
aster remain in relatively the same position as before. There appears 
to be no telophase to this division, but without entering into a rest stage 
the second polar body is given off. This arises from the same place as 
the first, pushing the latter farther outward or somewhat toward the 
side (Pl. XXI, fig. 3). Both finally le in the slight depression at the 
surface of the egg. The female nuclear elements still left within the 
egg then come to rest, at first lying closely against the cell wall below 
the polar bodies. The first polar body does not divide again immedi- 
ately and may never do so, though usually at a later period three are 
found. Ifit remains undivided the first polar body exceeds the second 
in size. 
With the close of maturation the sperm nucleus is seen to have moved 
upward through the yolk; its chromatic elements have become more 
evident several large nucleoli being present. The same is true of 
the female pronucleus. They now approach each other, and come to lie 
with their nuclear walls closely appressed (fig. 4), the egg nucleus lying 
