THE VEGETABLE CELL. 105 



at particular points or all over the tliallus, these cells falling upon 

 foreign bodies and becoming developed into new plants, if they 

 find a favourable station. But this phenomenon is to be regarded 

 a*s more or less a result of disease, for the normal development of 

 the thallus is interfered with by it, and if the formation of goni- 

 dia occm-s to a great extent, is perfectly arrested ; thus this mode 

 of multiplication of Lichens becomes the more inconsiderable in 

 proportion to that by spore^s, the more favourable the station to 

 the normal development of the plant, and vice versa. The same 

 phenomenon is met with again in the leaves of the Jungerman- 

 niese, which frequently break up more or less completely into 

 pulverulent masses of isolated cells ; but it has not yet been ob- 

 served whether these are capable of further development into new 

 plants. But the formation of the so-called gemonce occurs nor- 

 mally in many frondeseent Liverworts, especially in Lunularia, 

 Marchantia, and Blasia. These structures are developed, in 

 hollow receptacles of various form, from a stalked cell, which is 

 converted by repeated subdivision into a cellular nodule, which 

 becomes detached, readily strikes root, and grows up into a new 

 plant. (See Mirbel, ^^ Recherck 8. I. Marohantia polymorpha.") 



Far more important, or perhaps merely better known, through 

 the masterly researches of W. P. Schimper (" Bech, AnatoTn. et 

 MoTph. s. L Mousses'')^ than in the Liverworts, is the part played 

 by multiplication through independent gTOwth of single cells in 

 the Mosses, for almost every cell of the surface of these plants is 

 capable of conversion by repeated division into a cellular nodule, 

 which grows up into a leafy stem, whence is explained the extra- 

 ordinary diffusion of these plants, even of such species as never 

 bear fruit in particular localities. Schimper observed tins process 

 on the rootlets of the Mosses, partly directly, partly after they had 

 become converted into a green structure composed of confervoid 

 filaments, resembling the proembryo; he found the same pro- 

 embryo-like structure grow out from the leaf-cells of many species, 

 (e. c/., OHhotrichum Lyellii), and confirmed what Klitzing had 

 already seen, that even the cells of torn leaves will produce simi- 

 lar growths under favourable circnmstanees In paiiicular cases 

 also, compound organs (the leaves oi Mnium palustre^ M. anclTogy- 

 num, the antheridia of Tetraphis pellucida, &c.) are developed 

 into tuberous structures, spontaneously separating. 



From the fact that the cells of dijEfei*ent parts of the Mosses are ca- 

 pable of becoming developed into a bud or a proembryonal confer- 

 void structure producing a bud, it follows that in these plants, not- 

 withstanding their already rather complex sti-ucture, the subordi- 

 nation of the individual cell to the purposes of the whole is still but 

 small, and that the individual life even here readily acquires the 

 preponderance. But whether in the higher plants the individual 

 cell is still capable of coming forth independently in an analagous 

 manner and giving rise to the formation of a bud by development 



