60 
EDMUND B. WILSON 
In the mean time the small central triad breaks up into its 
separate components, which then pass to the poles in a very inter- 
esting fashion. This process always begins before the division of 
the large chromosomes, and is subject to some variation. Most 
frequently the three components draw apart in such a way as to 
leave the middle one lagging near the equator of the spindle while 
the others are proceeding towards the poles (figs. 3h, i). Often, 
however, one component first separates from the other two (figs. 
3j, k) ; but even in this case it seems probable that one of the latter 
is afterwards left lagging on the spindle, since later in the anaphases 
this arrangement is almost invariable. In these stages the middle 
component frequently becomes drawn out along the spindle to 
form a rod which finally passes to one pole to enter the telophase 
group (figs. 46,/). Half tiie secondary spermatocytes thus receive 
two small chromosomes and half but one, the respective numbers 
being 12 and 11. 
Two observed anomalies may briefly be mentioned. In two or 
three cases the middle component seems to be degenerating on 
the spindle (fig. 4gr) ; but if this be really the case it must be of 
rare occurrence, as is shown by the second division. Another 
interesting anomaly is shown in fig. Ah. Here there are appar- 
ently five small chromosomes, two of which are smaller than the 
others and are connected by a fiber as if they had recently divided. 
I am uncertain how to interpret this case, for one of the larger 
chromosomes (stippled in the figure) is paler than the others and 
lies at a lower level. This may be a fragment of the original 
plasmosome. If this be the case we have before us a case in which 
the central small chromosome has divided precociously. If all 
the five bodies, on the other hand be chromosomes, one of them 
would seem to be an extra or adventitious body, comparable to 
those described and figured by Paulmier in Anasa ('99, fig. 28a). 
c. The second spermatocyte-division 
As is to be expected from the asymmetrical distribution of the 
three small chromosomes in the first division the secondary sper- 
matocytes are of two classes. These divisions are very numerous 
