HoLLOWAY. — Studies ill the New Zealand Species of Ljcopodiuiii. 177 



tvpe of prothallus growing in rotting wood has lost the radial symmetry, 

 and consists of cylindrical but more or less clearly dorsiventral branches." 

 Curiously enough, Bruchmann himself does not read any signs of the 

 transition existing between the difPerent types of prothallus from the signifi- 

 cant variability of that of L. Selago. He gives to the prothallus of this 

 species the rank of a new type, and concludes also at the end of his paper 

 (5, p. 108), " From the above facts it follows that the above-treated-of 

 Lijcopodium groups, characterized especially by their generative generation, 

 do not stand to each other in near relationship — that is to say, not in such 

 as one would expect with plant species that are found in the same genus. 

 This knowledge leads to a separation of the lycopodiums into groups, or, 

 better still, into genera." However, the facts known concerning the ganieto- 

 phyte generation of the species which comprise the subgenus Urostachya 

 undoubtedly point to the fact that the two sections Selago and Phlegmaria 

 are closely related ; and, seeing that the species L. Selago is probably to 

 be regarded as the primitive type of the subgenus, if not, indeed, of the 

 whole genus, it follows that the PJdegmaria type of prothallus, which has 

 been found to occur in all the main divisions of the subgenus where the 

 species have an epiphytic habit, has arisen as a modification of the Selago 

 type in accordance with that habit of growth. One variation in the 

 prothallus of the New Zealand species, however, is not in accord with 

 the view that the series Selago-variimi-Billardieri-Phlegmaria represents a 

 linear series — namely, the paraphysis in the prothallus of L. varium and 

 L. Billardieri differs markedly in size from that of L. Selago, whereas 

 the L. Phlegmaria paraphysis is similar to the latter. This isolated fact 

 would indicate that evolution in the form of the prothallus in the subgenus 

 Urostachya has proceeded along several parallel lines, and that there are 

 to be traced, as Lang suggests (24, p. 313), " instances of independent 

 adaptation to similar conditions." 



I am not prepared in this paper to enumerate the variations in the form 

 of the sexual organs to be observed from a study of the different types of 

 prothallus as they occur in New Zealand, or to discuss the question of 

 their modification from the ancestral type in accordance with the form and 

 habit of the prothallus and sporophyte. Such a study has been suggested 

 to me by Professor Charles Chamberlain, of Chicago, in a letter in which 

 he points out the great interest that would come from seeing " what the 

 resultant between the force of heredity and the influence of environment 

 might have on the antheridium and archegonium and young embryo," and 

 I hope to be able at some future time to carry out the suggestion. 



The " seedling " plants of the New Zealand species which belong to 

 these two sections conform to the type described by Treub in L. Phleg- 

 maria and by Bruchmann in L. Selago. I have noticed no variations in 

 the New Zealand species. Bower (3, pp. 346-47) has expressed the view 

 that this type of embryo is the least modified in the genus. However, we 

 can see in the variation in length of the hypocotyl according to the depth 

 at which the prothallus grows another indication of the great plasticity of 

 the Lycopodium plant, which is to be noticed in almost every organ. 



Species belonging to the Sections Inundata and Cernua. 



In these sections there is less variability to be observed in the habit and 

 external form in the New Zealand species than in the last two sections. 

 However, in the gametophyte generation and the young plant there are 

 certain interesting modifications. 



