No. 466.) STUDIES ON PLANT CELL.— VII. 719 
out by the work of Farmer whose accounts of centrosomes and 
centrospheres in the germinating spores of Pellia and within 
the spore mother-cell of various liverworts, together with his 
account of a “quadripolar spindle" made it evident that the 
group offered some very interesting cytological problems. They 
led the author to the study Anthoceros (Davis, '99) and Pellia 
(Davis, :01), investigations which have been followed by Van 
Hook (:00) on Marchantia and Anthoceros, Moore (:03) on 
Pallavicinia, Chamberlain (:03) and Grégoire and Berghs (:04) 
on Pellia, while Ikeno (:03) has studied the processes of sperma- 
togenesis in Marchantia. 
My studies on sporogenesis in Anthoceros and Pellia led me 
to conclude that the processes of spindle formation did not 
differ in any essentials from those in the pteridophytes and sper- 
matophytes. There are present two successive mitoses and the 
spindles are formed from a surrounding mesh of fibrille devel- 
oped from the kinoplasm associated with the nuclear membrane 
and without achromatic centers (centrospheres or centrosomes). 
They exhibit clearly the free fibrillar type of spindle formation 
although in somewhat simpler form than in the pteridophytes 
and spermatophytes. The poles of the spindles generally end 
bluntly in areas of granular kinoplasm but these seem to me too 
indefinite in form to deserve the designation of centrospheres 
and such granular inclusions as may be present are too variable 
in number and position to be termed centrosomes. There is 
clearly present in Pellia during the prophase of the first mitosis 
a four-rayed achromatic structure which is later replaced by a 
typical bipolar spindle. This four-rayed kinoplasmic structure 
is evidently the same as Farmer's “ quadripolar spindle” which 
he described as associated with a simultaneous distribution of the 
chromatin in Pallavicinia to form at once four daughter nuclei. 
I was led to doubt this account and to suggest that the “quad- 
ripolar spindle" might prove to be simply a phenomenon of 
prophase associated with the peculiar four-lobed structure of 
the spore mother-cell in the Jungermanniales. I stated my 
belief that the distribution of the chromosomes during sporo- 
genesis in all liverworts would be found to take place through 
two successive mitoses after the usual manner. Moore (:03) 
