22 Wisconsin Academy of Sciences, Arts, and Letters. 
observed as they were liberated and swarmed about actively in 
the water. 
dSTo signs of degeneration have been detected in the anthero- 
zoids of Aspidium. So far as can be seen, either from a cyto- 
logical study of the development or from observation of the 
living antherozoids, the male cells here are perfectly normal. 
The Formation of the Apogamous Sporophyte in Aspidium 
Falcatum. 
The spores of this species germinate a few days after sowing. 
The short filament coming from the spore broadens at the apex 
and is divided into a narrow plate of cells. An apical notch 
is soon developed and the prothallium assumes the usual heart 
shape. The prothallium is never more than three cells thick 
excepting perhaps at the margin of a large apogamous out¬ 
growth. Glandular hairs are found along the margin and on 
the dorsal surface. 
Antheridial sacs, as has been described above, are developed 
in large numbers on nearly all of the prothallia. De Bary 
found archegones on twenty-five to thirty per cent of the 
prothallia of Aspidium falcatum. In my material, grown 
under the conditions described, archegones are of much less 
frequent occurrence. 
The apogamous outgrowths usually form when the prothallia 
are five or six months old. The time of their appearance 
varies considerably, however. In several cases a very young 
sporophyte was found upon a large prothallium eleven months 
old. A great majority of the prothallia produce sporophytes 
sooner or later. 
The position of the outgrowth is on the ventral side a few 
cells back from the apical notch. Since the prothallium is only 
two cells thick at this place, the outgrowth is certainly super¬ 
ficial and may be of epidermal origin. The origin of this out¬ 
growth has not been traced back to the first cell divisions, but 
figure thirty-eight shows a median section through an early stage 
in its formation. The little projecting mass of tissue, though 
