47 ° Stevens. — Spore Formation in Botrychium virginianum. 
ments of the cell demand. The evidence which Botrychium affords for this 
may be summarized as follows :• — In the prophases of the first division the 
density of the trophoplasm diminishes as the kinoplasmic spindle increases 
in size (Figs. 9 to 1 8). There is a gradual transition, both in structure and 
reaction to stains, from the kinoplasmic connecting fibres to the dense 
granular trophoplasm occupying the equatorial zone in the first telophase 
(Figs. 25 to 28). The trophoplasm as a whole becomes regenerated after 
the daughter-nuclei have entered into the resting-stage, and all kinoplasmic 
differentiations then disappear (Fig. 28). Later, the dense equatorial zone 
of trophoplasm gradually disappears as the kinoplasmic secondary connect- 
ing fibres are generated between the pairs of granddaughter-nuclei (Figs. 37 
to 41). And, finally, after the cell-plates demarking the granddaughter- 
cells or spores have been laid down, we find a gradual transition from the 
filar kinoplasm to the alveolar trophoplasm (compare Figs. 41 to 44 
inclusive). 
The plasmodium formed by the fusion of the tapetal cells continues to 
flow in between the groups of mother-cells while the division phases are 
progressing, until only a very thin layer of the plasmodium remains at the 
exterior. The plasmodium appears to be quite fluid, for very minute rifts 
between the mother-cells, sometimes not more than one micron in diameter, 
become filled by it. The nuclei of the plasmodium are unable to pass 
into the smaller crevices and so accumulate in large numbers where the 
spaces are larger, as shown in Fig. 47. 
After the disappearance of the connecting fibres of the second division 
the cell-plates thicken, nucleoli appear in the nuclei and the mother-cells 
become more or less dissociated from their previous grouping (Fig. 44). 
The middle lamella of the cell-plates separating the granddaughter-cells 
now becomes soluble and the granddaughter-cells or young spores become 
detached from each other while still enclosed within the membrane of the 
mother-cell (Fig. 45). Later, the granddaughter-cells become separated 
from the membrane of the mother-cell also and lie free within it (Fig. 46). 
The membrane of the mother-cells soon disappears and the granddaughter- 
cells then lie embedded in the tapetal plasmodium. The young spores now 
enlarge and build a nodulated wall about themselves which is differentiated 
into a relatively thick exosporium stained red by the safranin, and a thin 
endosporium stained violet by the gentian-violet of the three- colour-method 
(Fig. 48). As the spores advance in their development the tapetal plas- 
modium becomes strikingly depleted. Instead of the dense cytoplasm 
of the earlier plasmodium shown in Fig. 47 we find the vacuolate and 
attenuate structure of Fig. 48. The nuclei of the plasmodium possess 
at the same time a reticulum which also is depleted, the threads being 
thinner and taking the stain with less intensity. Their nucleoli appear, 
however, as in the earlier stages. 
