APPENDIX D. Ixxi 



membrane, and that they can multiply by sub-division. The 

 presence of the membrane has been denied by Caspary, JMohl, 

 and Gris, and also by the author of the article on ' Chloro- 

 phyll' in the Micrographic Dictionary, though the latter 

 admits that they undergo segmentation \ With reference 

 to these points, Dr. Hicks tells us that in some moss which 

 he cultivated under glass, ' the various branches threw out 

 numberless confervoid filaments, some of which approached 

 the radicular rather than the confervoid type.' In both 

 these kinds of filaments, however, he observed that their 

 chlorophyll granules possessed the power of enlarging. The 

 granules at first became more consistent on their exterior, at 

 the same time that they became larger. But Dr. Hicks 

 says: — 'As they increased they showed a more distinct out- 

 line, and it was clear that, whatever doubt might attach itself 

 to the existence of a membrane on the exterior of the 

 chlorophyll utricles of the leaves and ordinary confervoid 

 filaments, these contents were enclosed by a delicate en- 

 velope ; and, as they further enlarged, a nucleus appeared 

 in the centre. After a time, the parent cell broke up> and 

 these once chlorophyll utricles, but now distinct cells, be- 

 came free. ... In the undisturbed condition in which they 

 existed, and being held together by the gum-like character 

 of the residue of the parent-cell wall, they, of course, did not 

 spread far ; and, as the filaments had attached themselves to 

 the sides of the glass, I had an excellent opportunity of 

 watching their subsequent progress. . . . After increasing 

 gradually in an oval form, they arrived to about the xtW i^ 

 size, when they began to segment into" two, or three, or four 

 divisions, or even into more, a nucleus appearing in each 

 division. ... At this period the cell-wall of the parent- 

 cell (once chlorophyll utricle) was very marked. . . . After 



Linn. Trans.' vol. xxii. p. 580. 



