198 Transactions. 



experience in dissecting soon leads one to detect the presence of a central 

 region and so distinguish the prothalli from rootlets. Moreover, the 

 root-ends and vegetable fibres so commonly to be met with in the humus 

 are more dead-white or yellowish in appearance, the prothalli in their 

 fungus-free regions being somewhat translucent. Figs. 2-5 show the central 

 bulky region of four prothalli of L. Billardieri, from all of which the oldest 

 basal region is absent. The distribution of the fungus is indicated in these 

 figures by dark shading. It will be seen that the forward region of the 

 central prothallial body is the most bulky, and is wholly free from fungus. 

 It is also quite devoid of rhizoids. It bears on one surface — the upper — 

 paraphyses in large numbers, and also sexual organs. The archegonia and 

 antheridia are not intermingled, but occur in clearly defined zpnes arising 

 immediately behind the growing apex of the; prothallus. The surface 

 appearance of an old antheridium is shown^ in fig. 3a, the triangular 

 opercular cell being a very distinct feature. The imder-surface of the 

 generative portion of the prothallus is always quite naked and smooth. 



Lycopoditim variiim is closely allied to L. Billardieri, but grows terres- 

 trially and has a somewhat different habit of growth. Its prothalli are 

 in every respect identical with those of L. Billardieri. Three prothalli 

 are shown in figs. 6-8. That in fig. 6 bears a yoimg plant : its basal end 

 is not seen. That in fig. 7 shows the basal end dark and withered, and a 

 very young embryo can be seen through the tissues of the forward generative 

 region. In fig. 8 is shown a branched "resting" process. In none of 

 these figures is the distribution of the fungus indicated. 



Position in the Soil. 



The prothalli belonging to these three forms have apparently no regular 

 position relative to the surface of the soil in which they grow. The 

 branches of the prothallus extend in any direction. Frequently they are 

 inclined forward in the same direction as that of the growth of the main 

 body, but this is not always the case. Bruchmann has shown that in the 

 case of L. Selago the more deeply growing, elongated, cylindrical forms of 

 prothallus extend in a vertical direction towards the surface. This is not 

 thfe case with the prothalli of the terrestrially-growing L. varium, which are 

 quite similar both in their form and in their indefinite position of growth 

 to those of the ordinary epiphytic species. The prothalli of L. Billardieri 

 and of the two other allied New Zealand forms are, however, quite markedly 

 dorsi ventral in structure. The paraphyses and sexual organs are to be 

 found only along the uppermost side of the prothallus, whether they occur 

 on the central region or on the lateral branches. 



Early Stages in the Development. 



The youngest prothallus found by me belonged to the form L. Billardieri 

 var. gracile, and is shown in fig. 9. This prothallus consisted of the. fijst- 

 formed, conical region, which was entirely infested with the fungus and 

 was covered with the old bases of broken-off rhizoids, and a forward trans- 

 lucent region showing several young paraphyses and an antheridium im- 

 mediately behind the apex. This yoimger portion of the prothallus also 

 bore the usual long rhizoids. The fungus entirely occupied the main portion 

 of the prothallus except in its epidermal cells. It also bore a young lateral 

 process, on which rhizoids were beginning to arise by the outward growth 



