Nuclear Division in the Hepaticae . 499 
spore-mother-cells, as in the other plants, rest for a consider- 
able time before entering on their final divisions, and they 
also increase in bulk very considerably during this interval. 
The behaviour of the nucleus resembles that of Fegatella 
that it is not necessary to enter on details here, especially 
as I was not able to get an unbroken series of stages. The 
first mitosis does not result in a division of the mother-cell ; 
a cell-plate is formed (PI. XVII, Fig. 56), but it remains in 
a rudimentary state. Immediately after the first division, 
the two daughter-nuclei divide again (Fig. 57), and the 
resulting four nuclei take up positions similar to those 
occupied in a dicotyledonous pollen mother-cell (Fig. 58). 
The cell is then simultaneously divided into four daughter-cells, 
the protoplasm of which speedily becomes invested by a new 
membrane. The four cells then separate by the disintegration 
of the original wall together with the partition walls. 
Essentially the same course is followed during the spore- 
formation of Riella \ in two species of Marchantia , and in 
Fimbriarict* 1 2 , and they all differ from Fegatella in the spherical 
shape of their spore-mother-cells. It is a marked character of 
all these plants of the Marchantia-series that quadripolar 
spindles are not present. It is impossible to avoid the con- 
clusion that this is connected with the difference in the 
shapes of their respective spore-mother-cells at the com- 
mencement of nuclear division, especially the presence or 
absence of lobes. Targionia is an interesting form in this 
• respect. It does exhibit a slight amount of lobing, but 
unfortunately the spore-mother-cells are so exceedingly diffi- 
cult to fix that at present we can hardly speak very confi- 
dently about it. But in several cases I saw what I take to 
be quadripolar spindles, and I do not think that I have 
been deceived by mere contraction figures ; I hope, however, 
to re-investigate this plant when it next fruits. The great 
difficulty which arises in fixing the cell-contents arises from 
the frothy character of the protoplasm, which is filled with 
1 I am indebted to the kindness of Prof. Strasburger for material of this plant. 
2 Prof. D. H. Campbell kindly sent me material of this plant. 
