1899 | STUDIES ON REDUCTION IN PLANTS 21 
the second. It might, however, be admitted that they unite to 
form a continuous spirem, without invalidating the conclusions 
reached in this study, for I have not found the slightest evidence 
of a longitudinal fission during the daughter nucleus stage. On 
the other hand the chromosomes, as the nucleus opens out, 
appear in the same form and number as shown at the close of 
the first division, that is, in the form of a letter V or U, or in 
rings, or even in the form of paired rods, which form more or 
less the same figure, and agree in this respect with the same 
types described by Beliaieff for the same stages. 
The origin and form of the chromosomes in the first division 
of the pollen mother cell of Trillium, and the figures presented at 
the nuclear plate, show that the first division is heterotypic, 
though the transverse division of the chromosomes at this time, 
which indicates the tetrad character, is rarely present. The 
figures presented by the second division are exceedingly interest- 
ing, since they suggest the heterotypic division also, as is indi- 
cated by rings, in some cases, which are formed by the closing 
of the open ends of a V or U figure. There is thus a semblance 
of a heterotypic figure, with reducing or transverse division 
during the second mitosis in the sporogenesis of Trillium, and it 
would be interesting to know if the heterotypic figure described 
by Farmer’ during the second mitosis in the sporogenesis of 
some liverworts, results in qualitative reduction. The figures pre- 
sented by the chromosomes at the nuclear plate of. the second 
division are strikingly similar to those which exist during the 
true heterotypic mitosis, and the separation of the chromosomes 
gives, during the anaphase, figures exactly like those shown 
during the first division. 
A larger number of chromosomes in the second division, 
perhaps, are of the hooked form, and some are of the rod form, 
though both the hook and rod form are found rarely in the first 
division. It would appear that in Trillium, as well as in Arisema, 
as shown by my studies on reducing division in that genus, the 
7 FARMER, J. B.—On spore formation and nuclear division in the Hepatica. 
Ann. Bot. 9: 469-523. pl. 76-78. 18 95. 
