122 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
apart as the entire diameter of the spindle (cf. Plate 2, Fig. 18, and 
Fig. L, p. 77). I believe the facts can be better explained on the 
assumption that there is a marked attraction between the components 
of each pair, which results under ordinary circumstances in their lying 
close together, but would not prevent their being temporarily separated 
by various factors, such as the crowding of neighboring chromosomes, 
and the like. 
McClung (:05) has held that there may be a still closer association 
of the chromosomes in the spermatogonia. He asserts that in several 
Orthoptera a “‘precocious conjugation” of certain autosomes may 
occur at this early stage. ‘The rod-shaped autosomes become joined 
end to end forming a U-shaped element, to the center of which the 
mantle fibers become attached. I have no material from any of the 
species in which McClung found such precocious conjugation, with 
the exception of Chortophaga viridifasciata, but in this species I have 
been unable to find any evidence of conjugation in the spermatogonia. 
In fact, in my preparations of Chortophaga the chromosomes are, if 
anything, more widely separated than in most species. However, 
I have been able to find very few cells which afford a good view of the 
equatorial plate and these are all among the earlier generations. 
It is probable that in the later generations, owing to the decrease in 
the size of the cells, the chromosomes become more closely crowded 
together. It is possible that in some cases McClung has mistaken a 
univalent for a bivalent autosome. Apparently one of his chief 
reasons for considering certain autosomes in the spermatogonia to 
be bivalent is the fact that they are U-shaped — having the mantle 
fibers attached at the apex, and exhibit the so-called heterotypical 
form of mitosis. In Stenobothrus six of the spermatogonial auto- 
somes show these characteristics, and yet it is very certain that they 
are all univalent. 
3. SYNAPSIS. 
It is not my intention to attempt a: complete review of the already 
enormous literature on this stage in the development of the germ cells, 
but only to consider the more important results of some of the more 
recent investigations. ‘The term synapsis was first applied by Moore 
(95) to a stage in the early growth period when the chromatin is 
massed at one side of the nucleus, during which, as he believed, the 
reduction in the number of chromosomes takes place. Inasmuch as 
it has since been shown that in many cases no such contraction of the 
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