HoLLOWAY. — Studies in the New Zealand Species of Lycopodium. 227 



stage. There can' be no doubt that the symbiotic association of a fungus 

 with the Lycopodiiim prothallus is a further added feature, the mature form 

 of the Lycopodium prothalli being determined mainly by the nature of this 

 association. 



I found one very young prothallus of L. later ale which was entangled 

 in the rhizoids and lobes of the large prothallus shown in fig. 48. This 

 yoimg prothallus is shown in fig. 49. It consists of a filament of cells which 

 is green throughout, the filament being one cell in width in its lower half 

 and two cells in width in its upper. At' the apex there is a single small 

 cell which is clearly functioning as the apical cell. In this species also, 

 as in L. ramidosum, the primary tubercle is thus not invariably present. 



Main Body of the Prothallus. 



L. cernimm. — The main body of the prothallus of this species consists, 

 as has been described above, of one or more basal fungal regions, a longer 

 or shorter shaft, and a crown of lobes, at the base of which lies the meristem 

 and the generative region. Sometimes there is present also a lateral group 

 of lobes. As I have not seen Treub's original papers, I do not know whether 

 or not he has given in his description any indication of a differentiation of 

 structure in the fungus-bearing tissue, but, judging from the short siun- 

 maries of his results in various standard books of reference, this does not 

 seem to be the case. In the prothallus of this species as it occurs in 

 New Zealand I have observed that there is in this tissue a well-marked 

 differentiation. The fungal coils are invariably confined, so far as their 

 intracellular position is concerned, to the epidermal cells in the fungal area, 

 but the fungus always extends also in between the cells of the. adjoining 

 tissue. This will be apparent from figs. 39-44, which show the fungal 

 area in longitudinal section, and from figs. 66 and 67, which represent the 

 basal tubercle in transverse section. Moreover, this layer of cells which 

 shows the presence of the fungus in an intercellular position is always 

 modified in structure, the cells being very narrow, with their long axes 

 arranged at right angles to the peripheral fungal layer. A portion of the 

 fimgal region shown in fig. 41 is given in greater magnification in fig. 68. 

 In describing the " palisade " fungal zone in the prothalli of L. clnvatum 

 and L. annotinum, Bruchmann (1, p. 18) suggests that its main function 

 is to serve as a brace to the prothallus. This would seem to be the case 

 also in L. cernuum. In this latter species its peculiar structure is more par- 

 ticularly developed in those fimgal regions which extend up the shaft, and 

 where the need of a strengthening-tissue is felt. In those prothalli in which 

 a weU-formed, rounded primary tubercle is present the whole of the internal 

 tissue of the tubercle shows the intercellular fungus, but its cells are not 

 so markedly differentiated (figs. 38, 39). In the elongated prothalli of 

 L. ramidosum, in those cases in which the fungal areas are not much 

 swollen, the tissue in which the fungus is intercellular does not show much 

 modification in form. The fungus is chiefly apparent at the angles between 

 the cells, but it also seems to enwrap the cells generally (figs. 66-68). 

 I have not observed the presence of starch, as a rule, in the palisade cells, 

 but it is frequently thickly accumulated in the adjoining part of the shaft. 

 In the primary tubercle the cells are small and numerous (figs. 38, 39), 

 and the roimded form of the tubercle is probably due mainly to the 

 extensive cell-divisions, induced by the fungus, which there have taken 

 place. In this species the intercellular fimgus never spreads up the shaft 

 to any great extent. As has been described above, in this species there 



