52 Campbell. — On the Prothallium and Embryo of 
first root-hair may have precisely the same position as in the 
Polypodiaceae. 
Kny 1 and Luerssen 2 also emphasize the point that in 
O. regalis , and usually in Todea, no protonemal filament is 
formed, but that the first divisions form at once a cell-surface. 
While in the species here considered this was frequently met 
with in O. cinnamomea (Figs. 12, 13), it was very rarely the 
case in O. claytoniana , which in a large majority of instances 
formed a row of two or three cells before any longitudinal 
walls appeared, although such walls may subsequently form 
in the lower cells. 
In case the germination is truly bipolar, the exospore is 
pushed up with the growing prothallium, and forms a cap at 
its apex (Fig. 6), but if the root-hair is lateral, the exospore 
remains at the base of the prothallium (Fig. 7). 
While in O. claytoniana there are, as stated, several trans- 
verse walls formed before any longitudinal ones appear, in 
O. cinnamomea it is quite common, as in O. regalis , to have 
after the first transverse wall a longitudinal wall formed in 
each cell, so that the four resultant cells are arranged like 
quadrants of a circle (Fig. 12 c). One of the upper cells, as 
described by Kny 3 for 0 . regalis , becomes the apical cell of 
the young prothallium. When a protonema is formed, as 
usually occurs in O. claytoniana , the apical cell is formed as 
in the Polypodiaceae. After one or more transverse walls 
have been formed, an oblique wall is formed in the terminal 
cell, and immediately after a second one striking it at an 
angle of about 90°. The cell included between these walls is 
the apical cell, from which are formed two sets of segments as 
is usual in most fern-prothallia (Figs. 4, 10 x). From the 
time it is first formed, this cell continues to function as the 
apical cell until the prothallium reaches a considerable size. 
Very rarely the first wall in the prothallium-mother-cell is 
longitudinal as is often the case in Equisetum (Fig. 5), and 
sometimes the first divisions are in three planes so that a cell- 
mass is formed at once (Figs. 15, 19). 
1 L. c. p. 12. 2 See Schenk’s Handbuch, I. p. 171. 
3 L. c. p. 5. 
