296 Chromosomes in the Spermatogenesis of Anasa Tistis 
other ten large chromosomes. This secondary furrow is shown in both 
daughter eccentrics of Photo. 14, in one of the two of Photos. 15 and 16, 
and in one of Photo. 18. In all these preparations, except Photo. 17, 
the eleven chromosomes are clearly demonstrated at each pole. 
This closes the evidence we have to offer for the presence of an 
eccentric and often lagging chromosome in the first spindle. We have 
here demonstrated it in nineteen spindles and these photographs are 
chosen from a larger number showing the same phenomenon. We re- 
gard the demonstration of a lagging chromosome in the first spindle as 
important and suggestive, especially in view of the fact that it has 
been overlooked or ignored by the previous investigators of the sperma- 
togenesis of Anasa tristis. As stated above (p. 293), we believe that the 
frequently isolated position of this chromosome in the prophases offers 
at least a partial explanation of why it may lag in division, both in the 
first and in the second spindles. 
Photos. 19 and 20 show a very late prophase or metaphase of the sec- 
ond spindle and Photos. 21 and 22 metaphases in which the chromosomes 
are more nearly in line. In view of the characteristic position of the 
eccentric chromosome in all stages in which its identity is beyond ques- 
tion, we feel that in these preparations where its identity is not always 
clear we may at least tentatively identify it as the most isolated chromo- 
some of any given group. In Photo. 19, then, we would recognize as the 
eccentric, the slightly isolated chromosome at the right of the group— 
the eccentric of Photo. 20 as either the chromosome slightly separated 
from the lower left hand periphery of the group or the one slightly 
separated from the right periphery of the group. In Photo. 21. its 
identity is more obscure, but in Photo. 22 there is good reason for 
identifying it as the distinctly isolated chromosome at the right end of 
the line. The point we would make is that all the chromosomes we have 
identified as probably the eccentric show clearly the secondary furrow 
foreshadowed in this chromosome of earlier stages (pp. 288 and 291 and 
294-5). Even if we are mistaken in our identification of the eccentric here 
we cannot escape the fact that wherever it may be in each of these groups, 
it shows the plane of the next division, for every chromosome, even the 
microchromosomes, show a constriction. The presence of the furrow 
might be questioned for the dense chromosome close to the microchromo- 
some of Photos. 19, 20, and 21, because in this chromosome the con- 
striction is so delicate it may be obscured in the reproductions. In 
Photo. 22, however, we believe the reproduction cannot obscure the fur- 
row in any of the chromosomes. In any case, we do not believe that the 
