APPENDIX D. Ixxiii 



the filaments, the power of separating from the others, and 

 frequently it might be noticed that the cells had already 

 begun the process of division before their separation. The 

 production here of gonidia seems to result from a kind of 

 arrest of development. 



But Dr. Hicks speaks of still another mode by which free 

 cell elements may originate, when he says : — ' I have fre- 

 quently noticed that Gleocapsa-like cells are produced from 

 the contents of the cells of the older leaves, which, situated 

 at the base of the stem, towards autumn and during winter 

 and spring, have become brown. These leaves are not 

 wholly dead. . . . After a time the old cell-wall dissolves 

 away, and then it becomes evident that the contents have 

 assumed the form of, or rather have become a Gleocapsa 

 which certainly undergoes segmentation freely.' He has 

 seen considerable masses of Gleocapsa which have had this 

 mode of origin. 



Lastly, Dr. Braxton Hicks says ^ : — ' It seems to me 

 impossible to discriminate between the cells of the seg- 

 menting gonidia of Algae, of Lichens, and of INIosses ; and 

 hence I believe we shall be obliged to conclude that all the 

 cells classed as Palmellacese — Chlorococcus, Gleocapsa, Soro- 

 spora, and some others, with their so-called species— are but 

 varieties of one mode of simple vegetative cell-groivth, common to 

 most of the Cryptogamia ^. What is the value of the differ- 

 ences between each kind it seems difficult to decide, but it 

 may possibly be less than hitherto supposed.' 



The transformations of the gonidia of Mosses are, how- 

 ever, far outstripped by the metamorphoses of the antheridia 

 of Liverworts, if we are to rely upon the observations 



^ Loc. cit., p. 584, 



^ He has also seen growths of this kind originating by the segmental 

 multiplication of certain spores of Volvox. See p. Ixxxviii. 



