38 
W. E. AGAR 
(PI. 1/ fig. 6), but the general grouping of longer chromo- 
somes at one side of the equatorial plate and smaller ones at 
the other is evident. Much clearer figures are obtained in 
the case of the smaller spermatogonia with their comparatively 
short chromosomes (PI. 1, fig. 7). 
Since this characteristic grouping is present not only in the 
metaphase, but also in the anaphase, it must have the result 
that homologous chromosomes, or rather chroinosomic areas, 
are near one another in the resting nucleus. 
Besides this general arrangement of the large and small 
chromosomes, an examination of the figures gives one a very 
distinct impression that there is a tendency for pairs of 
chromosomes of equal size to approximate to one another. 
This is clearest in the small spermatogonia., both because of 
the greater simplicity of the figures, and also because the 
size differences seem to be emphasised in them. In PI. 1, 
fig. 7, the large V’s are closely approximated, and several 
other pairs can be made out. v 
This pairing of corresponding chromosomes outside the 
meiotic phase has been frequently noticed and taken to be a 
sign of a mutual attraction, which is brought to ahead in the 
meiotic prophase. Montgomery (1904) described it in the 
spermatogonia of various species of Amphibia, A. and K. E. 
Schreiner in Spin ax spermatogonia, and Muller in the 
somatic mitoses of Yucca. In this form the paired arrange- 
ment persists in the late telophase and reappears in the 
earliest prophase, and consequently it is a fair presumption 
that it is maintained throughout the resting nucleus. The 
most convincing case of all is that of Culex sp. (Stevens), 
in which the six chromosomes always appear in three obvious 
pairs in the pro- and meta-pliases of the oogonial divisions. 
The tendency of the smaller chromosomes to lie in the 
centre and the larger ones on the periphery can be seen in 
almost any polar view of a mitosis with marked size differences 
among the chromosomes. 
