480 Farmer. — On Spore- Formation and 
After the final separation of the chromosomes, each of the 
four daughter-nuclei becomes invested with its proper wall, 
and the spore-mother-cell becomes divided into the four 
spores, the protoplasm still retaining its singular vacuolated 
appearance (Fig. 13). The protoplasm of each spore imme- 
diately surrounds itself with its proper membrane, the endo- 
spore being shortly afterwards also differentiated. The wall 
of the spore-mother-cell then becomes mucilaginous, and the 
same is true of the partition-walls, and so the spores are ulti- 
mately set at liberty. The solution of these walls is not 
easy to follow. I have met with the best results by using 
orange G, which stains the swelling membranes deeply, and 
thus marks them clearly from the proper spore-membranes. 
The centrospheres have also long ceased to be recognizable, 
and apart from the radiations which characterize them during 
the active periods of nuclear division, there is no feature, in 
these cells, by which I find them to be distinguishable. The 
vacuolated and rather granular protoplasm, indeed, would 
seem to preclude any positive conclusion as to their per- 
manence being reached. 
Pellia epiphylla. 
The spore-mother-cells of Pellia epiphylla afford good 
material in which to study the changes which occur in nuclei 
and cytoplasm during the formation of spores. After the 
completion of the archesporial divisions, the spore- mother- 
cells become isolated from each other, and a considerable 
period of rest and growth intervenes before the two final 
mitoses take place. The effects of growth are manifested 
both in the cells as a whole, and also, subsequently, in the 
nucleus. As regards the entire cell, it conforms to, and 
indeed exaggerates, the type characteristic of the Junger- 
mannia series of Hepaticae. At first more or less irregularly 
spherical, it soon becomes four-lobed, and these lobes increase 
in size, chiefly owing to radial extension, so that the spore- 
mother-cell ultimately comes to consist of four large sacs 
whose cavities communicate with each other by means of 
