HoLLOWAT. — Studies in the New Zealand Species of Lycopodium. 275 



of this species that it goes on growing till it has quit€ lost its original 

 form. The specimen shown in fig. 47 was 8J mm. in height. The old 

 prothallus in fig. 53 was 5J mm. in height and 5 mm. in width, and 

 no less than 13 mm. (including the broken-off piece) in length. Fig. 49 

 illustrates an irregularly grown bulky prothallus, where the main lower 

 portion has become divided into two by a horizontal constriction. 



Summary . 



In summing up this section I would lay stress first of all upon the 

 fact that the study of the prothalli of the New Zealand species described 

 above introduces no new type differing in any great degree from the 

 five main types enumerated by such writers as Bruchmann, Lang, 

 Pritzel, Bower, and others. This is noteworthy, for it might have been 

 expected that, since the discovery of the prothalli of only eleven out of 

 the large number of modern species of Lycopodium had resulted in five 

 distinct types being recognized, a considerable increase in our know- 

 ledge of the Lycopod gametopln-te would reveal the existence of still 

 further types. The prothallus of L. ramulosum certainly presents re- 

 markable features, but these are to be regarded probably only as 

 variations from the L. cernuum type. Thus the results of the present 

 study lend additional weight to the theory that in the sexual genera- 

 tion of the genus Lycopodium we are to trace the influence of two main 

 factors — viz., epiphytism on the one hand, and a subterranean mode 

 of life on the other — the development of the various types from a rela- 

 tively primitive, chlorophyllous, and surface-living form having pro- 

 ceeded along these two main lines. 



A second point to be noted is that although the New Zealand species 

 of Jjycopodium prothalli conform to the types so well known from the 

 study of European and tropical species, yet in every case there are 

 interesting modifications to be observed. This emphasizes the fact that 

 the Jjycopodium prothallus is a most variable one. But, further still, the 

 nature of these various modifications may possibly be regarded as having 

 significance in indicating how the epiphytic and the subterranean types 

 have evolved from an original surface-living form, or even as supplying 

 actual links connecting the different types together along two such lines 

 of evolution. Lang and Bower both seem to consider the possibility of 

 the genetic relationship of the different subterranean forms of prothallus, 

 although they also suggest that they may be independent developments 

 from a common ancestor. The most noteworthy- variations from the 

 ordinary types which occur in the New Zealand species of prothalli are 

 as follows : The shaft of the prothallus of />. cernuum, may be rela- 

 tively long drawn out, suggesting the long cylindrical branches of the 

 prothallus of L. Selago and of the epiphytic prothalli. The leafly expan- 

 sions of the prothallus of L. Unterale are distinctly filamentous and more 

 branch-like than in the case of L. cernuum, and, moreover, these filament- 

 ous processes arise normally fi'om otlier parts of the shaft as well as 

 from its terminal region. The prothallus of L. ramulosum may be either 

 long drawn out, with a somewhat massive crown, or short and bulky, 

 with the shaft almost entii-ely suppressed and the crown greatly de- 

 veloped. Lang (14, i^. 306) has also emphasized the variability of 

 characters in the L. cernuum type which is known from the study of 

 L. inundatum and Jj. salakeiise, such as the pi'csence or absence of the 

 crown of lobes and the manifold branching from the primary tubercle, 

 features which seem to indicate a relationship between the L. cernuum 



