Wolfe, — Cytological Studies on Nemalion . 619 
When the fusion-nucleus returns to the basal portion of the carpo- 
gonium, division begins at once, and, as stated by both Wille and 
Janczewski, a basal cell is first cut off by a transverse wall. This cell 
usually undergoes no further division, but a single case was observed 
in which it divided once longitudinally ; suggesting that although it 
normally functions as a sterile c stalk-cell, 5 it may be considered as 
potentially similar to the primary sporogenous cell above it, from which 
the sporogenous filaments, or gonimoblasts, are developed. 
Wille has already noted that at the time of the division of the zygote 
into these two superposed cells, the chromatophore also divides (Figs. 
13 and 19). The history of this body, and of the chromatic elements 
as well, could not be satisfactorily followed through the two or three 
immediately succeeding divisions, owing to the intense staining of the 
surrounding cytoplasm. At the period, however, when the young cysto- 
Fig. 51. Mother-cells of carpospores proliferating from a subterminal cell. The walls of 
their predecessors persistent. (Optical section, x 1 500, reduced in reproduction.) 
carp consists of six or eight cells the divisions of nucleus and chromato- 
phore can be followed with certainty. These divisions present double 
the number of chromosomes characteristic of the thallus-cells. This 
phase of the subject will be more thoroughly presented in a subsequent 
portion of this paper. The details of the structure of the chromatophore 
can be seen at this period of development and its presence proved in 
every cell of the cystocarp, from such stages as are illustrated by Fig. 22, 
to the mature condition (Fig. 23). Its demonstration in the stages 
intervening between the two and the six-celled condition will no doubt be 
possible with the development of special technique. 
The gonimoblasts when fully developed are more or less copiously 
and repeatedly branched, and the cells in the peripheral region of the 
resultant structure ultimately give rise distally to numerous subterminal 
and terminal mother-cells, the contents of which, severing their protoplasmic 
U u 
