Osmunda claytoniana , Z M and O. cinnamomea, L . 51 
On crushing the spore, drops of a glistening substance, pro- 
bably a fatty oil, may often be seen, and small starch-granules 
are sometimes to be detected, but in small numbers. The 
chlorophyll is confined mainly to the central part of the spore, 
but a few chloroplasts extend to the periphery. 
By fixing the nearly ripe sporangia with a one per cent, 
solution of chromic acid, and imbedding in paraffin, the spores 
are easily sectioned, and the minute structure may then be 
readily studied (Fig. 2). The nucleus is rich in chromatin, 
and contains a single large nucleolus. The two spore-mem- 
branes are readily seen in such preparations. 
The Germination of the Spores. 
The spores germinate promptly if placed in water or on 
damp soil, this taking from 24-48 hours, depending upon the 
temperature. The exospore bursts along the three ridges, and 
the spore-contents, now invested with an evident cellulose 
membrane, protrude through the aperture (Figs. 1 c, 3). 
The first division takes place after the spore has elongated 
slightly, and is usually at right angles to its longer axis. The 
resulting cells are of very unequal size, the larger becoming 
the mother-cell of the prothallium, the other simply elongating 
and forming the first root-hair. Unlike most ferns, the root- 
hair here contains considerable chlorophyll, although less than 
is found in the prothallium mother-cell. The first cell-wall in 
the latter is usually parallel with that that separates the root- 
hair ; but not infrequently, especially in O. claytoniana (Figs. 
4 a, 7), it makes a considerable angle, even a right angle in 
some cases, with the first wall, so that the axes of growth of 
the first root-hair and prothallium make an angle of 90° some- 
times, instead of being the same. Kny 1 lays considerable 
stress upon the bipolar germination of the prothallium of 
Osmunda , as distinguished from that of the Polypod iaceae, 
where he regards the first root-hair as lateral ; but my ob- 
servations have shown that, especially in O. claytoniana , the 
1 Kny, 1. c. p. 12 . 
E 2 
