246 N. M. Stevens, 
The two strands are always more or less twisted, but the ends are 
occasionally free. Large granules are usually seen in connection 
with these chromosomes. 
The chromosomes in the equatorial plate of the first polar 
spindle (Boverr 1890 and fig. 1, 6, 7, 8, 12) are split twice longi- 
tudinally forming a tetrad similar to that of Ascaris, but differing 
less in appearance from the ordinary chromosome, as the components 
of the tetrad lie very close together and are very long in pro- 
portion to their diameter. Comparison of a polar and a lateral view 
of the spindle reveals the fact that the split which shows in a 
polar view — that which corresponds to the second maturation di- 
vision — is somewhat wider than that seen in a lateral view. An 
end view of a tetrad also shows a difference in the thickness of 
the components of the tetrads in the two diameters, as seen in 
Fig. 14a. These facts as to the composition of the tetrad incline 
one to believe that we have here a bivalent chromosome with the 
two components paired longitudinally instead of end to end. If this 
is so, the first division divides both of the original chromosomes 
longitudinally, and the second division separates the chromosomes 
forming the pairs. The split observed in an earlier stage (Fig. 13) 
is probably a temporary separation of the longitudinally paired 
chromosomes. 
In nine out of twelve ripe eggs of one individual, there were 
two polar spindles. These spindles were in various positions with 
respect to one another and to the egg-membrane, — 1) end to end and 
tangential, 2) parallel and radial (Fig. 15), 3) end to end and radial 
(Fig. 16). The two spindles seemed in most cases to be exactly alike. 
In one egg they were so close together as to form one very broad 
spindle, and in another the poles of the two spindles were united 
at one end but separate at the other (Fig. 17). The chromosomes, 
however, showed only one longitudinal cleft, indicating that the 
division of the first polar spindle had been completed, though this 
usually occurs only after the eggs are laid. One of these spindles 
is evidently the 2d polar spindle (Fig. 16 a) and the other corresponds 
to the division of the first polar body which has not been separated 
from the egg (Fig. 16b). An end view of a dyad taken from one 
of these spindles in equatorial stage is shown in Fig. 14b. In two 
eggs the spindles were in a late anaphase (Fig. 17), and the 
chromosomes were evidently the separated components of the dyads. 
The only explanation of this abnormality seems to be that laying 
