6j6 Graham . — Nuclear Division of Preissia commutata . 
It has been stated that groups of plastids lie in the cytoplasm around 
the nucleus (Figs. 1, 7). In many sections four groups were well defined, 
and it was at first thought that these groups might bear some relation to 
the number of spores formed ; that is, that each group constituted the 
plastids found in a mature spore. More than four groups were, however, 
found in sections obtained later. From metaphase to telophase the plastids 
are almost always divided into two large groups that lie near the poles of 
the spindle, few or none lying in the cytoplasm near the equator of the 
spindle (Figs. 13, 14, 15, 18). The coarse strands of cytoplasm extending 
from the groups of plastids to the nuclear membrane are very prominent 
(Fig. 26), but whether there is any relation between these strands and tfye 
spindle fibres was not determined. 
During the earliest prophases a most careful search was made for 
centrospheres and centrosomes. The membrane of many nuclei in all stages 
of prophase was closely searched for a body exerting a pull on the 
membrane. None was found in Preissia commutata. Centrospheres with 
a centrosome have been described by Farmer (’ 95 ) in the earliest prophases 
of the spore mother-cells of Fossombronia Dumortieri. He also observed 
that the nuclear membrane of this plant was pulled out through the 
influence of the centrospheres, and that the quadripolar spindle is at first 
a ‘ nuclear distortion Farmer (’ 95 ) found that the spindle in Pellia 
epiphylla was also formed through a pull exerted on the nuclear membrane 
as described above for Fossombronia Dumortieri. Not having found spindle 
fibres while the nuclear membrane was still intact, nor that the nuclear 
membrane was pulled out, I am unable to say whether Preissia commutata 
agrees with Fossombronia Dumortieri and Pellia epiphylla or not. In view 
of the presence of the hyaline kinoplasmic caps described above in Preissia 
commutata , and the work of Nemec (’ 99 ), Rosen (’ 95 ), and others, in which 
it is shown that spindle fibres are developed in the hyaline kinoplasmic 
caps, it is probable that at least the outer spindle fibres in the plant now 
being considered are formed from these caps. Heretofore these hyaline 
kinoplasmic caps have been reported only in somatic or vegetative cells, 
and their occurrence in the heterotypic division of Preissia is therefore 
interesting. 
Summary. 
1. In early prophase the nucleus of the mother-cell enlarges. The fine 
reticulum of the resting cell is changed into a coarse network of threads, 
some of which can be traced for some distance. The individual chromatin 
bodies increase in size and number. 
2. The nucleus continues to grow. The reticulum is replaced by 
a leptonema spireme. Many strands lie side by side. 
