158 Davis. — Nuclear Studies on Pellia . 
the position of the cell-plate. The facts agree well with the 
theory recently advanced by Timberlake (’00) that kinoplasm 
is actually drawn to the cell-plate by the contraction and 
transformation of the spindle-fibres. According to this view 
Fig. 11 presents a spindle shortened to the form of a barrel 
between the daughter-nuclei. It is important to note that 
the cellrplate is laid down in Pellia after the usual manner in 
the Pteridophytes and Spermatophytes. 
The writer’s studies on Anthoceros (Davis ’ 99 . p. 103), led 
him to the conclusion that, the cell-walls dividing the spore- 
mother-cell bore no relation to spindle- fibres, but were formed 
from films of protoplasm that developed between the pairs 
of nuclei and chloroplasts. The nuclear figures of the second 
mitosis in Anthoceros are so small that the difficulty in 
following the fate of the spindle-fibres was frankly acknow- 
ledged. They seem to entirely disappear before the cell-plate 
is laid down, the latter being first a delicate film held in place 
by numerous strands of cytoplasm. It is of course possible 
that this film is composed, at least in part, of material 
derived from the spindle-fibres, but such a relation could not 
be traced. The writer suggested that the film might be 
independent of the spindle-fibres and related to the plasmic 
membrane (Hautschicht). Perhaps more favourable species 
of Anthoceros may make clear the difficulty 1 . It is certainly 
important that we should emphasize the fact that the process 
of cell-formation in Pellia agrees in all essentials with that 
found in the higher plants. 
The daughter-nuclei following the first mitosis pass quickly 
into a condition in which the chromosomes break up into 
1 Since the above was written observations have been published upon a species 
of Anthoceros more favourable for study (Botanical Gazette, xxx. 395, 1900). 
Mr. J. M. Van Hook was fortunate in having material of an Italian form whose 
cells are larger than in our native species and yield more clearly the details of 
structure. He has established the presence of a small cell-plate between the 
daughter-nuclei after the second mitosis with the usual relation to connecting 
spindle-fibres. This cell-plate determines the position of the conspicuous film 
of protoplasm that later becomes transformed into the cell-wall. Thus Anthoceros 
presents no obstacle to extending through the Liverworts the general rule of 
cell-formation exemplified in higher plants. 
