HoLLOWAY. — Studies in the New Zealand Species of Lycopodium. 187 



re-examining my serial sections for the purpose of this paper I found that in 

 one or two instances the second fungal swelling was associated with the 

 development of assimilating lobes arising laterally on the prothallus-shaft 

 and on the opposite side of the swelling. The prothallus of L. cernuum is 

 thus in a somewhat plastic condition, and the variations in form which are 

 to be observed make it easier to institute comparisons between this type of 

 prothallus and those of the other sections of the genus. 



In my previous description of the prothallus of L. laterale (16, p. 265) 

 I noted that, as in L. cernuum, the shaft is variable in length, the shorter 

 prothalli having thus a somewhat solid, compact appearance, and that the 

 leafy expansions on the crown of the prothallus of L. laterale are less lobe- 

 like and more filamentous than in the case of the other species. Another 

 character noted was that these assimilating outgrowths occur also normally 

 in a lateral position on the shaft of the prothallus. The presence of a long, 

 narrow, club-shaped process attached to the tubercle of two of the prothalli 

 was also mentioned, and I was inclined to regard this as the actual first- 

 formed portion of the prothallus and not as a branch arising from the 

 '■ primary " tubercle. As in the prothallus of L. cernuum, the fungal zone 

 may extend for a certain distance up one side of the shaft, giving rise to 

 a second swelling distinct from the lower one. In none of my preparations 

 did I find that the interior cells of the swollen areas which adjoined the 

 fungus-infected peripheral cells were so clearly differentiated as a distinct 

 fungal tissue as they are in the largest prothalli of L. cernuum. The fungus 

 extends between these cells, in one particular instance as far as into the 

 lower region of the shaft. These cells have without doubt a definite arrange- 

 ment, with their long axes at right angles to the peripheral layer, but in 

 longitudinal and transverse section they appear little differentiated in form 

 from the other cells of the shaft. Thus the fungus zone in this species is 

 of the same nature as that in L. cernuum, but it shows a somewhat less 

 degree of differentiation of its tissues. I found one very young prothallus 

 of this species entangled closely amongst the rhizoids of an older prothallus. 

 It consisted of a filament nine cells long, the older half of this prothallus 

 being but one cell wide, and the younger half two cells wide. At the base 

 of the prothallus was to be seen the original spore, and four or five rhizoids 

 were borne on the older cells. There was no suggestion of a primary 

 tubercle, nor was the presence of a fungus to be seen, but all the cells 

 showed numerous chloroplasts. This young prothallus may be compared 

 with those of the same early stage in L. ramulosum, described below. 



The prothallus of L. rainulosum is very variable in form (16, pp. 269-71), 

 much more so than that of the other two species. The long-drawn-out 

 forms Jiave several swollen fungus-infected areas, bearing rhizoids, some 

 of the largest prothalU showing as many as five such areas. Each of these 

 fungus swellings has usually a group of assimilating lobes associated with 

 it, and at the base of the lobes antheridia or archegonia are developed. 

 Not infrequently the form of the prothallus is strangely altered owing to 

 the fact that a somewhat massive body of tissue is formed at a place where 

 a group of lobes is associated with a fungus area. Generally the last- 

 formed uppermost part of the prothallus is the bulkiest, but two or even 

 three such masses of tissue are often to be seen in these long-drawn-out 

 forms of prothallus. In every case in which a young plant was attached 

 to a prothallus it had developed from the uppermost of these bulky regions. 

 One or two prothalli were found which had branched at the point of a 

 swollen fungal region, the two branches being equally developed. As well 



