NOTES ON THE DIVISION OF THE CELL AND 
NUCLEUS IN LIVERWORTS. 
By J. M. VAN Hook. 
(WITH PLATE XXIII) 
In the following pages are presented the results of some 
observations on the division of the cell and nucleus in the spore 
mother cell of Anthoceros, and in the vegetative cells of the 
gametophyte of Marchantia. 
But little has been done in the cytology of the Hepaticae, 
aside from a study of the development of spores. Several papers 
were written by Farmer (’94—’95), whose detailed work has 
dealt, for the most part, with the cytology of reproductive cells. 
Along this same line Davis (’99) has worked out spore forma- 
tion in Anthoceros, and his article upon ‘‘ The spore mother cell 
of Anthoceros”’ strongly suggested the desirability of extending 
the study. 
My observations on Anthoceros confirm his statement con- 
cerning the absence of centrospheres, but in regard to the 
disappearance of the connecting fibers and the formation of the 
_ cell plate by the thickening of strands of apparently undifferen- 
tiated cytoplasm which extended between the daughter nuclei 
my own results differ from his. 
A cell plate seems to be formed in no wise different from 
that found in Marchantia, an account of which is given below, 
7. é., the cell plate is laid down through the instrumentality of 
the connecting fibers (figs. 11,13). Cytoplasmic strands similar 
to those figured by Davis are always found between the chloro- 
plasts (fig. rz), but are undoubtedly around the spindle; and 
when a section includes only these strands, or if the connecting 
fibers be insufficiently stained, the appearance figured by him 
(his fig. 25) is presented. The same aspect is also displayed 
at a later stage, as in his fig. 26, but I am inclined to attribute 
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