96 BOTANICAL GAZETTE [AUGUST 
It appears to the writer that plant cytology has a very important 
field open for investigation dealing with the structure of the 
chromatophore and its place in ontogeny. 
We pass now to the second part of the paper, which is to 
consider the behavior of the nucleus in sporogenesis. The 
structure of the spore-mother-cell and process of nuclear division 
in Anthoceros was first described by Strasburger (’8o, p. 162). 
The following account entirely supports the essentials of those 
observations, but the present investigation attempts a molt 
detailed examination of nuclear activities, involving the prob 
lems of spindle formation, synapsis, the succession of mucleat 
divisions, and formation of the walls between the spores. 
The fact has already been stated that eight chromosomes at : 
present in the sporophyte, and consequently enter the nucleus 
of the spore-mother-cell. This nucleus in a resting condition § 
very similar to the nuclei of the archesporium and_ shows vel) 
little structural differentiation (fig. 3). It is small and its linin 
network is very inconspicuous, but the nucleolus is prominent 
Coincident with the appearance and increase in size of the | 
chloroplast the nucleus enlarges (figs. 4, 5, 6) and the threads ol 
linin become very prominent. They are so exceedingly small, 
however, that it was not possible to determine accurately the | 
structure, even with a Zeiss apochromatic immersion lens under 
the magnification of 2250 diameters. Dark-staining minute 
bodies along the linin thread are presumably granules of chro- 
matin, but their distribution could not be ascertained with or 
tainty, nor was it possible to follow the convolutions of - 
Spirem. 4 
