4 PAULINE H. DEDERER 
In earlier eggs, before or at the time of laying, a clear pale vitel- 
line membrane may be seen beyond this. The polar bodies are 
formed in the dense granular layer, very near the middle of the 
anterior end, just within the cone-shaped area. 
The earliest nuclear stage obtained after the growth of the 
egg, is the late prophase, found in eggs which had not been 
laid (fig. 3). The chromosomes, 13 in number, lie enclosed within 
the nuclear membrane, near the surface of the egg, in the same 
position as the first maturation spindle. The chromosomes 
are smooth, elliptical or dumb-bell shaped bodies, almost equal 
in size. Later the nuclear wall breaks down, the spindle fibers 
_ appear and the chromosomes become arranged upon them pre- 
paratory to division (figs. 4-5). When first placed upon the 
spindle, the chromosomes do not all show a dyad form, but 
later a median constriction appears in each one. The spindle 
lies obliquely to the surface of the egg. The spindle fibers can 
rarely be traced to a point of convergence, and no centrosomes nor 
asters appear. Various cytoplasmic bodies lie near or attached 
to the spindle (fig. 4), but they are not constant in size or num- 
ber, and often cannot be detected. They are present only dur- 
ing the metaphase. 
In figures 6 and 7 are shown two first division groups. ‘There 
is but slight difference in the size of the chromosomes, and each 
one appears to be separated into two equal parts. On account 
of their small size they were at first interpreted as chromosomes 
of the second division, but a further study showed that this was 
not the case. There was no trace of a first polar body, nor of 
sperm within the egg. Moreover, the eggs had not been laid, 
but were taken from a moth which had just begun laying. 
Figures 4 and 5 and numerous other undoubted first metaphase 
stages, with larger chromosomes, were obtained from the same 
lot of eggs. Restaining and extraction had practically no ° 
effect in altering the size difference which remains unexplained. 
In twelve cases I found chromosome groups similar in size to 
those shown in figures 6 and 7. These figures seem to indicate 
that the chromosomes divide equally in the first division but a 
