256 
C. F. r. MKEK. 
spindles often appear to be distorted, and tlie distances- 
between the poles may consequently be greater than those 
shown. The fact that no such distortion is observed in the 
sperinatogoninl and secondary spermatocyte mitoses suggests 
that the large size of the primary spermatocyte cells renders 
section-cutting, however carefully carried out, destructive of 
the true form of the spindle in certain cases. Such cells, 
however, may be recognised, because the spindle-fibres appear 
to be abnormally bent and twisted, and are often disconnected 
from tlie centrosomes. After careful consideration I am there- 
fore satisfied that the measurements given represent accurately 
the dimensions within the cell. 
The Length of the Mitotic Spindle at the Conclusion 
OF THE Secondary Spermatogonial Metaphase. 
M^e will now consider the spermatogonial mitosis, and try 
to discover if a constant exists also for this metapliase. Figs. 
34 to 37, PI. 17, are drawings of polar views of tliis metaphase,- 
showing all tlie chromosomes. Fig. 38 represents a polar 
view of one daughter-plate in the earliest anapliase. Tlie 
complex appears to be composed of two concentric rings of 
fourteen and eiglit chromosomes respectively, while two chro- 
mosomes lie at the centre ; this is the arrangement seen in 
figs. 34, 35, 37 and 38. In fig. 36, thirteen chromosomes 
constitute the outer ring, and nine the inner ; but this arrange- 
ment may have resulted from abnormal movement caused by 
the process of section-cutting. The cliromosomes tliat are 
short rods lie on the spindle in a manner such that their major 
axes are parallel to the equatorial plane, and thus differ in 
position from those of the spermatocyte metaphases. 
Fig. 39, PI. 17, is a drawing representing a lateral view of the 
equatorial plate before constriction of the bivalent chromo- 
somes has begun. The centrosomes of this cell are shown in 
fig. 72, and the length of the spindle is found from this draw- 
ing to be 6’6 u- Fig. 40 is a lateral view of the equatorial plate 
at a slightly later stage, when the dyads have begun to- 
