HoLLOWAY. — Studies in the New Zealand Species of Lycopodiuin. 185 



plant and of its vascular tissues. The stem-anatomy of only one other 

 species belonging to these two sections has been examined — viz., that of 

 L. inundatum, described and figured by Jones (21). His figure of the tetrarch 

 structure and broad protoxylems in a small branch of this species corre- 

 sponds very closely with what I have observed in the corresponding parts 

 of the plant of all four New Zealand species. The cortex in the New 

 Zealand species varies very markedly. The position of the sclerenchyma 

 zone in L. cernmim is outermost, in L. ramulosum it is median, and in 

 L. Drummondii and L. laterale it is innermost. There is a distinctly spongy 

 region of the cortex in the three latter species which is quite in accord 

 with the nature of their habitat. The external position of the sclerenchyma 

 in the stems of L. cenumm is perhaps to be explained by the fact that these 

 are above-ground, and that this species seeks drier situations than do the 

 other three. It is not quite so clear, however, what is the particular 

 physiological reason for the median position of the sclerenchyma in the 

 cortex of L. ramulosuw unless it be because in this species the innermost 

 cortex is used as a storage zone. 



The Prothallus. 



The prothallus of these two sections, so far as it is known, belongs to the 

 L. cernwim type, and this is one of the main arguments which determines 

 that the two sections together form one of the natural divisions of the 

 genus. However, the prothalli of all the species that have been examined 

 show striking variations from the typical form, and in the case of the three 

 New Zealand species, L. cernuuni, L. laterale, and L. rarmdosimi, there is 

 a wide range of variability in the form of the prothallus in each individual 

 species. In fact, in these species there is a far greater degree of plasticity 

 shown by the gametophyte generation than bv the matiire sporophyte. 

 This is to be expected, for whereas on the one hand the species are limited 

 in their distribution, and hence the sporophyte is under a comparatively 

 constant set of external conditions, on the other hand the prothallus, 

 being very delicate in nature and combining the chlorophyll condition 

 with the saprophytic, must necessarily show considerable variation from 

 the typical form in accordance with the varying depth at which the spores 

 germinate. In these two sections of the genus, in contradistinction to 

 what obtains in the other sections, the prothallus lasts for only one season. 

 The spores germinate only in consistently damp, loose soil, more especially 

 that which possesses a thin covering of short moss. Being partly dependent 

 upon the presence of light, they cannot germinate at any great depth in 

 the soil, but yet amongst the moss and other delicate debris of vegetable 

 matter there is, of course, a considerable range of variation in the conditions 

 under which the development of the prothallus must take place. 



The prothallus of L. iniindatmn has been described by Goebel (14). 

 This corresponds fairly closely with the L. cernuum type. Treub (30) has 

 described the prothallus of L. salakense, a species which is apparently a 

 variety of L. cernuum. This he says belongs to the cernuum type, but it is 

 not so closely similar to it as is the prothallus of L. inumlatiim . Several 

 filaments may develop from the primary tubercle, one of these afterwards 

 developing into the main prothallus-body. There are no foliaceous lobes 

 ])roduced on the crown. 



Treub has given a very full account of the prothallus of L. cernuum. 

 I have not had access to his original papers, and hence am not aware 

 whether or not he has described in the case of any of his specimens the 



