314 Mr. G. H. K. Thwaites on a peculiar state of the Palmellese, 



branched filaments in the Coccochloris rubescens, Brebisson, as 

 well as in the above-named Palmella. This is rendered more 

 interesting from the circumstance of the Cocc. rubescens being 

 one of the species in which M. de Brebisson, as stated by Mr. 

 Ralfs*, has observed conjugation taking place, a process which 

 will probably be found to be general amongst the Palmellece, and 

 to be the true mode of reproduction in all the species. 



Upon comparing the filamentous condition of the Palmella, as 

 above described, with one of the lower Fungi — with a Botrytis, 

 for example, — we might at first feel disposed to conclude that in 

 one as in the other the cells terminating the filaments are to be 

 deemed the true reproductive organs, since in both species the 

 cells become detached and give origin to structures having no 

 organic connexion with the original ones. Upon reflection, 

 however, we shall find that very different is the relation in 

 which the detached cells of the Palmella and those of the Botrytis 

 stand to the filaments from which they have respectively become 

 separated. In the Botrytis the plant has reached its perfect 

 development, and the terminal deciduous cells are evidently 

 the reproductive spores ; but the Palmella is in an immature 

 state, and the branched filaments may more correctly be com- 

 pared with the mycelium of the higher Fungi, or with the early 

 confervoid filaments of the Mosses. In the Palmella the separa- 

 tion of the cells from the filaments may be considered as really 

 a subdivision of the plant — a gemmation — a multiplication of 

 the individual rather than a reproduction of the species ; and the 

 subsequent fissiparous division of these detached cells into other 

 equally independent organisms as a continuation of the process 

 of gemmation ; the individual plant itself being the aggregate 

 of all the cells so produced previously to true reproduction taking 

 place. 



It is very interesting and important to observe the extent to 

 which the process of gemmation takes place in the lower tribes 

 of plants, and this is especially evident in the Mosses. From 

 the negative evidence adduced by Bruch and Schimper, there can 

 be little doubt that the theca of the moss, with its contents, is 

 the product of the fertilization of the pistillidium. It would fol- 

 low then that the theca and the entire mass of sporules contained 

 within it are equivalent to one embryo of the flowering plant, 

 and that consequently the subdivision of this reproductive matter 

 into a number of sporules is equivalent to the multiplication of 

 the individual plant by a process of gemmation ; — that in fact it 

 may be termed an intra- thecal or sporangial gemmation. Again, 

 in tracing the development of one of these sporules after its 

 escape from the moss-theca, we find that it gives origin to a con- 

 * Ralfs's ' British Desmidieae,' p. 37. 



