34 Lang. — Prothalli of Ophioglossnm pendulum 
siderable length. Its lower portion bears spent antheridia, 
while towards the apex mature and young antheridia are 
found. 
The prothallus represented in Fig. 35 is of interest, since it 
presents characters intermediate between those of the typical 
male and female prothalli. Its vegetative region is larger and 
more strongly lobed than in the male prothalli, while the 
sexual region, though shorter and thicker than in the latter, 
is of considerable length. A number of antheridia are present 
on its lower part, while above these archegonia have formed. 
The more ordinary type of female prothallus is illustrated by 
Figs. 36 and 37. In these the lobed vegetative region forms 
the greater part of the prothallus, the sexual region being very 
short and wide : both these prothalli bore embryos. 
The general structure of the prothalli will be evident from 
the diagrams (Figs. 38-40), which represent in longitudinal 
section one of the youngest prothalli, a full-grown male and 
a female prothallus respectively. In all the diagrams the 
region occupied by the endophytic Fungus is shaded, and 
the position of the sexual organs is indicated ; these charac- 
terize the vegetative and sexual regions, which have already 
been distinguished in considering the external morphology. 
In the young prothallus (Fig. 38) the sexual region is still 
relatively small, only a few antheridia (an.) having been 
produced behind the apex (a.). The beginning of the forma- 
tion of lobes of the vegetative region is seen at l.l. The 
further growth of the older male prothallus (Fig. 39) is seen 
to have been mainly due to the increase in length of the 
sexual region, the vegetative region having in this case 
become only slightly lobed. In the female prothallus 
(Fig. 40), on the other hand, the region containing the 
endophyte is large and strongly lobed, while that bearing 
the archegonia (ar.) is short ; owing to the presence of 
a fairly large embryo on this prothallus the apex could 
not be distinguished. A few antheridia are present behind 
the archegonia ; they are indeed in such cases often situated 
on the region containing the Fungus. All the diagrams 
