196 THE Lire HISTORY OF 
these younger regions, however, the rhizoids penetrate the bark of 
the tree and then draw the prothallus down against it. The 
rhizoids may be formed in clusters (f. 7) from an undifferentiated 
cell of the prothallus, or from a proliferation consisting of a single 
cell. Rarely more than one rhizoid originates from a single cell. 
The rhizoids are long colorless structures rarely branching near 
the apex, and sometimes distended at the base (/ 73). 
The prothallium is occasionally monoicous-autoicous, but 
more frequently pseudo-dioicous with the antheridia and arche- 
gonia produced indirectly from the same plant. In such instances 
the archegonia are borne on the main prothallium, which also pro- 
duces gemmae from which antheridia originate. 
Barrel-form or spherical sterigmata containing chlorophyl 
arise from the margin, apex and occasionally from the middle of 
the prothallus bearing gemmae in great numbers. A sterigma 
may give rise to one or several gemmae, and these gemmae may 
divide repeatedly before falling off. The gemmae may either lie 
on the surface of the prothallus or stand out from it after the 
manner described by Goebel, who found the first position assumed 
in Vittaria elongata and the second in Monogramma paradoxa 
(f. 19-25)* A sterigma may give rise to several sterigmata 
before the gemmae are produced (f. 22). The gemmae are very 
similar to those of Vittaria elongata as described by Goebel and are 
in the form of spindles composed of § to 11 moniliform cells (f. 
25, 29). The terminal cells may give rise to rhizoids, but these 
and the antheridia may be produced from any one of the cells of 
the spindle (f. 30-33). The gemmae produce prothallia in va- 
rious ways, and also may develop other gemmae, and antheridia 
(f. 33-37). 
ANTHERIDIA.— The antheridia are produced either directly 
m one or more cells of the gemmae (f. 39, 40), or on the 
ower surface of the prothallium, the margin and occasionally on 
iam upper surface. A prothallium sometimes bears both antheridia 
ws سس‎ 7 36). The development of the antheridia is 
È in any one of the positions named sends out a 
protuberance containing chlorophyl which becomes club-shaped 
“Gobel X Mali dal Das Gon. a i 
و‎ os pholog e and Biologische Studien, Ann. Jard. Bot. Bui- 
