186 
George Arnold 
In Fig. 24, a, b and c, tliese shapes are shown on the left, and 
ou tbe right, the shapes in which they appear when just dividing. 
The shape figured in C. Fig. 24, shows traces of a longitudinal split, 
which beconies more marked when division takes place, and give it 
the typical tetrad shape. This split merely foreshadows the division 
in each half which will take place in the 2nd. meiotic division, as 
has been shown to occur in a large number of animals. Holmgren 
(’03) describes such chromosomes in the Ist. maturation division of 
Silpha carmata, but overlooking the well-known fact just mentioned, 
has jumped to the conclusion, unsupported by any other evidence, 
that each such chromosome is quadrivalent. The anaphase and telo- 
phase are illustrated in Figs. 20, 22, 23 and 19, and call for no 
special notice. 
We will now return to the nucleolus. In the metaphase, it has 
definitely assumed the shape shown Fig. 24 d’, and as remarked 
before, lies nearer to one of the poles than to the equatorial plane, 
but is outside the spindle. It moves dose up to the pole by the 
time the anaphase sets in, and on the Separation of the two daughter 
cells of the Ist. meiotic division, it lies extremely dose to the 
dump of chromosomes (Fig. 23, N), and is eventually enclosed in 
the new nuclear membrane which is formed. There is a definite 
prophase, but not of long duration, which precedes the 2nd. meiotic 
division, and during all that period this nucleolus can be seen in 
half the cells, together with the nucleolus which is formed in each 
of the daughter cells shortly after the new nuclear membrane is 
formed. 
Thus half the cells of the 2nd. meiotic division show in the 
growth -period two nucleoli (Fig. 27, n and K), and the other half 
only one nucleolus (Figs. 26 and 28, n). Bot these nucleoli gradually 
disappear, becoming fainter, and leaving no visible traces by the 
time the 2nd. maturation spindle is completdy formed (Fig. 31). The 
nudeolar nature of these bodies (especially the one derived from 
the Ist. maturation division) is more completdy proved by a series 
of careful counts, made over a sufficiently large number of cells in 
the Ist. and 2nd. meiotic divisions, from polar and lateral views. 
Out of 100 counts of Ist. meiotic 
85^ gave 15 gemiui and the nucleolus. 
7X „ over 15 „ ,, „ „ 
8^ „ under 15 „ ,, „ „ 
