148 SYDNEY H. VINES. 



hyphse penetrate into this excrescence as it forms, and the result 

 is that these microscopic grains possess the two structural ele- 

 ments of a Lichen. It occasionally happens, however, as De 

 Bary^ has shown, that they have no hyphse. They are then simply 

 Nostocs which entirely resemble those which are to be found 

 amongst Mosses. Nearly always in such cases the >oungXostoc 

 which is attached to the Collema only by a slight gelatinous 

 pedicle, becomes detached. 



He goes on to cite other examples of the same kind with the 

 view of proving that the gonidia can easily take on the charac- 

 ters of free Algae and vice-versa. He concludes this part of his 

 paper by referring to the genus Lichina, expressing an opinion 

 that the gonidia of this genus are formed by filaments of some 

 Eivularia, an opinion which was fully borne out by Kny's re- 

 searches upon the development of the thallus of Lichina pi/gniea,^ 

 which were published later in the year. 



Having brought so much evidence to prove the identity of the 

 gonidia of many Lichens with certain of the lower Algae, he 

 goes on to discuss objections which might be raised again^^t this 

 view, such an objection, for instance, as that raised by Korber 

 (see ante), that these Algae are not autonomous organisms but 

 simply the gonidia of Lichens in a free state. Such an hypo- 

 thesis, he says, is quite inconsistent with our present know- 

 ledge of Algae, for it is certain that these same Algae do not 

 multiply merc4y by division, but also by a fructification of their 

 own which is quite distinct from that of the Lichen. He then 

 briefly gives an account of various investigations which have been 

 made into the life-histories of the gonidia, such as Famintzin 

 and Baranetzky's discovery of zoospores in the Ci/stococcus 

 humicola extracted from the thallus of various species of Lichens, 

 his own observations of the emission of zoospores by Trentepohlia 

 which furnishes the gonidia of Opegrap/ia varia, and draws at- 

 tention to the similarity, amounting to identity according to 

 Pringsheim, of Phyllactidium which furnishes the gouidial 

 element of Opegrapha fUcina, with Coeleochaete.^ Here then 

 are numerous instances of the multiplication of gonidia by cer- 

 tain specialised reproductive processes, and many instances of the 

 kind may be cited as occurring amongst those gonidia which 

 belong to the Phycochromacae. 



He concludes by recounting his experience of separate cul- 

 tures of gonidia, and of spores of Lichens. The former multi- 

 plied immensely but no trace of a hypha could be detected — the 

 latter germinated and grew, but no gonidia were developed. 



» ' Ilandb. d. ]'liys. B..t.,' 13d. ii, Abtli. i, p. !290. 



2 ' Sitzbcr. d. gescllscli. naturf Freunde iu Jicrliii,' Nov., 1874. 



^ See this Journal, vol. xv, p. 334. 



