102 BOTANICAL GAZETTE [AUGUST 
second mitosis are much smaller. However they exhibit a 
essentially similar structure, having flattened poles without cen- 
trospheres. Several prominent fibrils make up the center of the 
spindle which is bordered by an ill-defined set of mantle fibers, 
The polar view of a spindle shown at the left of fig. 24 demon 
strates that four chromosomes are present at the nuclear plate, 
the same number that appears during the first mitosis. Prophast 
and anaphase conditions of the second mitosis are found otly 
with great difficulty and are very unsatisfactory for study becast 
of the small size of the elements involved. 
The four nuclei that result from the second mitosis associate 
themselves each with one chloroplast, and with these become dis- 
tributed symmetrically through the cell, so that the protoplast 
naturally segregates into four regions representing what are later 
to become the tetrahedral division of the spore-mother-cell (figs 
26, 27). The spindle fibers disappear completely. 
The problem of the splitting of the chromosomes engage! 
the writer’s attention, but it must be plain that Anthoceros * 
not a favorable subject for the study of this process. The neatly. 
spherical form of the chromosomes offers immense difficultits ! 
orientation. Farmer (’95) reported some peculiar conditions " 
the forms studied by him, which he considers as illustrations 
the ‘‘heterotype”’ division described by Flemming. They res 
from the habit that the chromosomes have of doubling on the™ | 
chromo | 
selves and then being pulled apart as V-shaped daughter 
somes. The figures are very complex, but Farmer ass 
that the division is really longitudinal and not transverse, so that 
it cannot be interpreted as qualitative. In Anthoceros all eviden® 
ures & 
the daughter chro ;, eight in number, arranged in four pa : 
Such a Stage is shown in jig. 23, and the grouping certainly 1” 
cates that each of the original four chromosomes has divi 
tudinally into halves. It is not at all unusual to find HE) | 
sets of daughter chromosomes placed as in fig. 22, which ™ : 
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