of Lycopodium clavatum , L. 
289 
The Young Plant. 
It has been mentioned already that three of the prothalli 
bore young plants. These were of different ages, but none 
were young enough to afford information as to the embryology. 
Figs. 23 and 24 represent two of the prothalli. The one in 
Fig. 23 is seen from the end, and shows a young plant, the 
leafy stem of which had already attained a considerable length, 
while the first root is still unbranched. In this and another 
example the plants occupied a position on the marginal ridge 
corresponding to the younger archegonia in Fig. 8. Here, as 
in L . annotinum , the plants remain attached to the prothallus, 
which, however, had ceased to produce sexual organs, until 
they have attained a considerable size. The peculiar form of 
the prothallus represented as seen from above in Fig. 24, 
appears to have been due to an injury at an earlier stage 
of development. One-half appears to have been partially 
destroyed and had ceased to grow, while from the opposite 
margin a new growth of semicircular outline had proceeded ; 
the light colour of the latter contrasted with the older portion, 
which was dark brown in tint. Two of the last-formed arche- 
gonia must have been fertilized about the same time, for the 
young plants were almost exactly similar in form and size. 
The longer cylindrical body projecting from the ruptured 
archegonium-wall is the shoot, the scattered scale-leaves 
of which were inconspicuous, while the primary root is recog- 
nizable as the short conical projection at the base of this. 
It may be noted that the orientation of these two plants with 
regard to the edge of the prothallus is the same. 
No structure comparable to the protocorm of L. cernuum 
was recognizable on external examination of the young plants, 
and its absence is further shown by the outline drawings 
in Figs. 25 and 26, which represent sections through the 
young plants in Fig. 24. In Fig. 25 the section passes in the 
median plane of the first root, but owing to the shoot being 
curved to one side, fails to follow the latter for any length ; 
