i 70 Davis . — Nuclear Studies on Pellia. 
The poles of the spindles, as shown in Figs. 39 and 40, are 
entirely free from radiations or bodies resembling centrosomes, 
and they may be broad so that the bundles of fibrillae stand 
out clearly from one another. The writer can find nothing 
in the events above described to justify a belief that an aster 
is really present in the vegetative cells of the seta. It cannot 
be found with the resting nucleus or at the poles of the 
spindle, and certain appearances during early prophase are 
readily explained by the peculiar arrangement of the proto- 
plasm in the cell 1 . 
General Considerations. 
We are hardly prepared as yet to draw general conclusions 
on the cytological conditions in the Hepaticae, but some 
peculiarities appear conspicuously, and certain possibilities 
may be noted. 
It would seem, from the studies on Pellia , that the morpho- 
logical manifestations of kinoplasm may be remarkably 
various in the same life-history. Indeed there seems to be 
no fixity of structure apart from the finely granular condition 
that precedes mitosis. It is true that we have in the delicate 
granules (microsomes) of this protoplasm the forerunners of 
fibrillae, and the latter in turn organize the asters, but it has 
been generally considered that the asters are to a great 
degree permanent in the cell. 
We have examined three important phases in ontogeny of 
Pellia , (1) sporogenesis, (2) the germination of the spore, 
and (3) vegetative activities in the seta, but there has been 
no agreement in the form assumed by the kinoplasm during 
mitosis. In the first instance fibrillae, acting largely inde- 
1 Mr. Van Hook (’00) reports a centrosome with radiations in the archegonio- 
phore of Marchantia. This structure was first visible in the prophase at the poles 
of the elongating nucleus, and was not observed after the radiations disappeared. 
The suggestion is presented that it is * a temporary body.’ In this respect it agrees 
with the centrospheres in the gametophyte of Pellia and in the kinoplasmic caps 
in the seta of the sporophyte. It seems probable that in Hepaticae centrospheres 
and kinoplasmic caps will be found to be related structures, the former but a more 
highly differentiated condition of the latter. 
