ELIMINATION OF SEX CHROMOSOMES 481 
size as the chromosomes. Side views of the polar spindle, of 
which four are given, each with three chromosomes, show these 
to be of equal size. One of two cases of an egg nucleus (just 
prior to the formation of the spindle) also shows six equal chro- 
mosomes; the other case shows four equal chromosomes and 
one of double size that no doubt represents two chromosomes 
overlapping or else stuck together. 
When these chromosome plates are compared with those 
of the female-producing egg shown in fig. LX, page 255 of my 
paper (’09), the size relations seem to be about the same. Only 
four plates of these eggs were found. I suspect that one of the 
equatorial plates that is assigned to a male-producing egg, 
namely, fig. LX; AK, really belongs to a female-producing egg. 
Occasionally it is difficult, owing to the obliquenessof the sections, 
to make sure that a particular egg is a large or a small one. 
If this egg is excluded, or referred to the female-producing series, 
there remain fourteen equatorial plates of male-producing eggs. 
In all of them one chromosome is noticeably smaller than the 
rest. I can now add four more chromosome groups of male-pro- 
ducing eggs to this list, figs. 1, 2,3,4. Three of these are equa- 
torial plates or just prior to that phase, and the fourth shows 
the chromosomes in the nucleus just prior to the spindle stage. 
They all contain five larger chromosomes, and one much smaller 
than the other five. 
It is true that there is some variation in the relative size of 
the chromosomes in all of these figures, which makes it difficult 
to express exactly the relative sizes of the different chromosomes, 
and therefore I am aware of the danger of attempting to distin- 
guish between the plates of the male- and female-producing eggs; 
‘yet the presence of the very small chromosome is so distinctive 
of the smaller eggs that I believe no error is committed in attribut- 
ing to this difference at least a real significance. 
If the two kinds of chromosomal groups just specified are 
significant one should expect to find a similar difference in the 
somatic cells of the individuals that give rise to these eggs, for 
since each of these individuals produces only one kind of egg 
(all the eggs found in one individual are male-producing or female- 
