208 Transactions. '• 



one another, representing quite distinct Lycopodiaceous stocks. This was 

 the conclusion arrived at by Treub from his study of the prothalli and 

 young plants of several species belonging to the Selago, PJdegmaria, and 

 Cernua sections, and by Bruchmann also from his study of the prothalli of 

 several European species. Lang, however, pointed out (24) that in spite 

 of the great differences existing between these types there was a common 

 fundamental structure to be traced in all, and that the various modifica- 

 tions of this structure were all obviously in accord with the particular mode 

 of life peculiar to each prothallial type. He stated his belief that it was 

 the change from the self-nourishing chlorophyll condition to a saprophytic 

 condition of life which has determined the lines upon which the Lycopodium 

 prothallus has evolved, and he pointed to the variations which are known 

 to occur in the prothallus of L. Selago as illustrating clearly how it has 

 been possible for the more modified types of prothallus to arise. Further, 

 taking into account the fact that the mode of life of the different types of 

 prothalli, as exemplified in the twelve species whose prothallus was then 

 known, was in close accord with the habit of the sporophyte generation, he 

 suggested that it was possible that the genetic affinities of the species of 

 Lycopodium will be found to coincide exactly with the biological divisions 

 of the genus. 



The facts which I have brought forward in this paper relating to the 

 variations of the main types which occur in the New Zealand species, 

 and also to the great range of variability which the individual species show 

 under the manifold external conditions under which they are found in this 

 biological region, seem to be thoroughly in accord with Lang's suggestion. 

 Not only do the prothalli of these species provide transitions between the 

 main types in the same sense as does that of L. Selago, but so also do the 

 other main characters ; in fact, these variations show that the whole geiius 

 is in a state of great plasticity, and that the various types of habit and 

 external form of the sporophyte, of the nature of the fertile region, of the 

 vascular anatomy, and of the form of prothallus and young plant, can be 

 best explained only by viewing them together as adaptations which have 

 proceeded more or less hand in hand. 



At the same time, the eleven New Zealand species bring to light no 

 new main types either of prothallus, of young plant, or of stelar anatomy. 

 Our knowledge of these species serves to emphasize the fact that there are 

 three main cycles of affinity to be distinguished in the modern genus — 

 namely, the Selago- Phleg mar ia group, the Inundata-Cernua group, and the 

 Clavata grouji. In the different parts of this paper I have tried to institute 

 a distinction between characters which are recent and adaptive and those 

 which are phylogenetic, and in the light of these facts have expanded more 

 fully the conchisions with regard to the interrelationships of these main 

 groups which I reached in a former paper (16, p. 302). Stated briefly, these 

 conclusions were that the Selago section must be held to comprise the most 

 primitive and least modified members of the modern genus, and that the 

 Phlegmaria and Clavata sections have been independently derived from it, 

 the former being less modified than the latter. The Inundata and Cernua 

 sections I suggested should best be placed in a group apart, as having been 

 derived from ancestors common to themselves and to the Selago section but 

 independently of the latter. I will now proceed to sum up the results of 

 the present paper in terms of this thesis. 



The statement that the Selago section comprises the most primitive 

 members of the genus by no means suggests that with respect to all its 



