254 
C. F. F. MEEK. 
immediately above it. Constriction of the chromosomes is in 
progress in fig. 11, and is completed in fig. 12; in figs. 
lo, 14 and 15 the daughter-chromosomes appear to be moving 
further and further apart. The centrosomes of these cells are 
represented by figs. 54 to 58 respectively ; and these drawings, 
made at a magnification of 889 diameters, are respectively 
identical with those given in figs. 49 to 53. These measure- 
ments, which have been made from cells belonging to the 
testes of a single specimen, can leave little doubt that the 
length of the spindle at the conclusion of the metaphase is a 
constant for this cell generation of the individual. 
We must now ask if this constant may be assumed for all 
members of the species. Figs. 16 to 20, PI. 17, are drawings of 
the equatorial plate of five cells in the testes of a second 
specimen, and each is seen to correspond exactly with the two 
•drawings placed immediately above it. Fig. 16 shows a late 
metaphase, which is found to be concluded in fig. 17 ; figs. 18, 
19 and 20 represent successive stages of the anaphase. Figs. 
•59 to 63, PI. 17, show the centrosomes of these cells, drawn at 
a magnification of 889 diameters. And, since these drawings 
are respectively identical with figs. 49 to 53 and 54 to 58, we 
have reason for believing that the spindle length is a constant 
-at the conclusion of the secondary spermatocyte metaphase 
in all specimens of F. auricularia. 
The Length of the Mitotic Spindle at the Conclusion 
OF THE Primary Spermatocyte Metaphase. 
Having discovered a probable constant for the spindle of the 
secondary spermatocyte metaphase, we will consider the primary 
spermatocyte mitosis. Figs. 21 to 24 represent polar views 
of the metaphase, and all the chromosomes are shown ; fig. 
25 is a drawing of the slightly later stage when the daughter- 
chromosomes have begun to move towards the poles. As in 
the secondary spermatocyte metaphase, the major axes of those 
•chromosomes that are short rods are at right angles to the 
