ty pd Howe And UNpbERWooD: THE GENUS RIELLA 
spores. The involucres are less globose and more pointed at the 
apex than those of &. Cossoniana. Judging from two specimens 
of R. Cossoniana collected by Professor Trabut, R. affinzs has the 
appearance of being a larger species with broader lamina, though 
this might not appear from a comparison of the measurements 
given above with those given by authors for R. Cossomiana. Our 
specimens of #. affints are prostrate and more or less entangled 
with mud and are so delicate and fragile that it is quite possible 
that the measurements in the above description may fail to do full 
justice to the height of the plant. It may be remarked that in 
occasional capsules the spores though showing a well-developed 
brown coloration have short spines or papillae much like those 
of R. Cossoniana ; such spores are always smaller than is normal 
for the species and are probably immature or else have ripened 
under abnormal conditions. 
Our experiments in germinating the spores of Riel/a affinis 
have been more successful than those with the spores of Aze//a 
Americana, though they were not begun until December, 1902, 
five and a half years from the date of collection of the specimens. 
More than half of the spores experimented with germinated in a 
few days by being placed on a piece of wet filter-paper in a glass 
dish kept in a moist chamber at ordinary living-room tempera- 
tures. The germ-tube in practically all cases emerges, as in X. 
Americana, from the outer or more spiny face of the spore, usually 
near its middle. The root-hair follows a little later, its lumen re- 
maining continuous with that of the germ-tube. The length of the 
germ-tube varies exceedingly. Finally, there appears in it a some- 
what curved transverse wall with its convexity turned toward the 
spore. The part above contains most of the starch grains and in 
the course of time begins to show chlorophyll, cell-divisions mean- 
while taking place as described above for R. Americana. The 
length of the germ-tube from the spore-wall to the curved septum 
has been observed to vary in different cases from 0.02—0.7 mm. 
One or two root-hairs, in addition to the one which comes from 
the base of the germ-tube, may spring out later from some part of 
the filamentous stalk of the young gametophyte. The forms as- 
sumed by the young gametophytes are extremely varied and are 
doubtless determined to a considerable extent by the conditions of 
