HoLLOWAT. — Studies in the Nexv Zealand Species of Lycopodium. 203 



the actual apical merist^m is somewhat ventrally placed. Fig. 20 shows 

 this forward region of a prothallus in longitudinal section, but the older 

 vegetative region is not included, as the prothallus was curved in shape. 

 The generative region in longitudinal section is also shown in figs. 11 

 and 34, both of which prothalli bear a young, developing plant. 



Fig. 20. — L. Billardieri. Central body of the prothallus, showing 

 generative region in longitudinal section, and also a 

 lateral branch. Basal cone of prothallus not included. 

 X 70. 



The Lateral Branches. 



The lateral branches or vegetative processes arise from the main central 

 body when the vegetative region of the latter is ceasing to cope with its 

 main function of nourishing the growing generative region. The examina- 

 tion of such prothalli as those given in figs. 1,9, and 10 shows both that the 

 rhizoids on the older portion of the main body have decayed away and 

 that the fungal coils in the cells of this older region have given place to the 

 fungal " spores." The cells are full of these spores, which in all the old 

 prothalli that I have examined do not seem to disintegrate further. The 

 lateral branches are thickly covered with rhizoids, and show the presence 

 of a fungus distributed in the cells more or less along their entire length. 



The tissues of the branch are similar to those in the vegetative region 

 of the main body, except, of course, that in accordance with the smaller 

 girth of the branch both the fungal zone and the centrally-placed con- 

 ducting-strand are there correspondingly less in width. Fig. 21 shows a 

 well-developed branch in transverse section, and fig. 22 in longitudinal 

 section. In transverse section there is seen to be a central group of six 

 fungus-free cells, surrounded by a single layer of larger fungus-bearing 



