HoLLOWAT. — Studies in the New Zealand Species of Lycopodium. 235 



passes over into the elongated cylindrical main body which bears sexual 

 organs on the dorsal side, so becoming bilateral. The prothalli of L. Selago 

 grow upright in the soil. They either preserve the cone form throughout 

 their life — being, however, much smaller than the prothalli of the clavatum 

 or complanatmn tj^es- — or they give rise to elongated bilateral extensions 

 of portions of the upper margin of the cone. In the upright prothalli of the 

 clavatum and complanatum types there is practically no disposition towards 

 elongation, the cone form being preserved throughout the life of the 

 comparatively massive prothallus, any extra meristematic activity showing 

 itself merely in irregular lobing of the upper margin or in adventitious 

 budding. The angle of divergence of the cone from its apex upwards is 

 different in these two t}'pes, being greater in the former than in the latter, 

 so that the mature forms of the two prothalli are somewhat different. The 

 prothalli of the species which belong to the Cernua and Inundata sections 

 are also upright in growth, and have a radial build, so that in transverse 

 section the main body is circula^r in outhne, but the cone form is not always 

 present, Treub's description of the prothalli of L. cernuum suggested that 

 a short cone-like stage always followed immediately upon the germination 

 of the spore, and the " primary tubercle," as it was called by him, was thus 

 looked upon as a characteristic feature in this type of prothallus. In all 

 the species of this type whose prothalli are known a primary tubercle is, 

 indeed, often present, but not invariably so, as appears, for example, in 

 the prothalli, both young and old, of L. ramulosum. 



The cone form adopted by the Lycopodium prothallus must be con- 

 sidered along with the presence in its tissues of the symbiotic fungus. It 

 is, of course, well known that this fungus is one of its most characteristic 

 features, just as it is also of other subterranean pteridophytic prothalli. 

 Treub states that the prothallus of L. salakense shows no fungus, and it is 

 quite possible that other species belonging to either the Cernua or Inundata 

 sections may prove to be without it. From what we know of the young 

 prothallus of L. laterale and L. ramidosum it would seem that in the 

 sections Cernua and Inundata the infection may be jjostponed considerably, 

 for the fungus is frequently absent altogether from young prothaUi of quite 

 fair size, and also not infrequently mature prothalli show signs of the same 

 initial fungusless region at their base. 



In the prothallus of Tmesipteris the fungus is found even in the basal 

 filament, when that is present ; but whether the infection is initiated from 

 the very first or subsequently spreads back into the extreme lower parts 

 of the prothallus is not known. I have found many prothalli of Tmesipteris, 

 both yoimg and also mature, which showed a short filament of cells at 

 their base, and also, on the other hand, complete prothalli in which no 

 filament was present, in the latter case the remains of the original spore 

 being sometimes clearly apparent on the cell at the actual apex of the 

 basal cone. Sometimes the Tmesipteris prothallus takes the form of a 

 steadily tapering cone, and at others in its lowest regions it increases in 

 girth by a progressive series of gentle swellings. One cannot avoid the 

 suggestion that the dominating factor in the Tmesipteris prothallus is the 

 presence of the fungus, the nature of the swelling being due to the con- 

 sistency or intermittency, as the case may be, of its activity, and the 

 omission of a filamentous stage being due to its very early entry into the 

 germinating spore. When we turn to the prothalli of the Lycopodiaceae 

 the same conclusion seems to be forced upon us. Large mature prothalli of 

 L. rarmdosum may show no primary tubercle at all, and the cone form may 

 be altogether absent, so that the general form of this prothallus can then 



