1914] SetcJidl: Parasitic Florideae, I 5 



V. .AIORPIIOLOGY 



All the species of Janczewskia thus far puhlishod and all those 

 investiii'ated by the writer agree in certain g-oneral details of structure. 

 They all possess certain organs of contact or even of penetration of 

 the host plant, all po&sess a basal structure or tubercle made up of 

 coalescent branches to form a solid tissue, and all possess branches 

 projecting more or less from the wart, in some species conspicuously 

 free, but in others barely projecting beyond the surface of the tubercle. 

 The degree of extension beyond the basal tubercle varies in the same 

 species according to the nature of the individual plant, projecting 

 more in the cystocarpic and tetrasporic plants and much less, as a 

 rule, in the antheridial plants. For general discussion, it seems best 

 to consider here only the facts as published by Solms-Laubach (1877) 

 and by Falkenberg (1901) for Janczewskia vemicaeformis and for 

 J. tasmanica, since these two species represent the extremes of structure 

 thus far discovered in the genus. 



The details of the penetration of the host by the parasitic Janc- 

 zewskia have been followed in both species. Solms-Laubach (1877. p. 

 220. pi. 3, fig. 16) describes the penetration of the host, Laurcncia 

 ohtusa, by a young plant of Janczewskia verrucaeformis, as being 

 etfected by filaments resembling the hyphae of a fungus. These hyphal 

 filaments are numerous, extending into the tissues of the host, pene- 

 trating between the epidermal cells of the host and filling the spaces 

 between the interior cells without, however, entering the cells them- 

 selves. The hyphal filaments form a more or less extended network, 

 are flexuous, and are composed of elongated cells which differ from 

 those of the rest of the parasite in shape and smaller dimensions. 

 Falkenberg (1001, pp. 259, 260, pi. 24, fig. 17) describes and discusses 

 a very young plant of Janczewskia verrucaeformis, just at the stage 

 of breaking through the epidermis of the host. The stage described 

 and figured is just where the mouosiphonous. or "protonema." stage 

 ceases, and the outer portion is passing over into the complex shoot 

 which is to develop into the tubercle. The inner mouosiphonous 

 portion has already penetrated into the host, where it is to establisli 

 pit connections with the internal cells of the host and act as nii 

 haustorium. Falkenberg {loc. cit., pi. 24, fig. 16) also figures the 

 haustoria in a somewhat older plant of J . verrucaeformis. The haus- 

 toria of J. tasmanica (cf. Falkenberg, 1901, p. 258, pi. 24. figs. IS. 19) 

 resemble those of J. verrucaeformis in being penetrating hyphal lila- 



