118 PROCEEDINGS OF THE AMERICAN ACADEMY 



comes impossible to distinguish the cells, which had a common origin 

 (Fig. 12). The original filament cell does not increase in diameter 

 with the diaphragm cells, but becomes elongated with the other fila- 

 ment cells (Fig. 2). 



It will be observed from the figures that the filaments that come 

 from the apical cells nearest the middle of the cluster (Figs. 5 and 6) 

 show more divisions than the others in the space above the young 

 diaphragm (Fig. 8). The cells derived from them reach the centre 

 of the diaphragm, while the others do not (Fig. 9), and these filaments 

 are the first to give off bulb-cells below the diaphragm (Fig. 10). 

 With the exception of the branches given off to form the diaphragm, 

 the filaments do not branch. Each filament is perfectly simple and 

 straight from its base to the apical cell at the other end. 



The question as to the origin of the branches naturally arises now. 

 I have not been able to get the earliest stages, but I am sure they are 

 to be looked for very close to the apex of the plant, for the nearer you 

 get to the apex the smaller branches you find. Occasionally, to be 

 sure, branches a few chambers long may be found below much larger 

 branches ; but still I think these are formed earlier than those above 

 them, but are prevented from growth by some accident. It seems 

 probable that the branch will be found to arise by division of one of 

 the outer cells, already described as the result of the cell division close 

 to the apex. At any rate, a branch was seen to spring from a point 

 directly opposite a filament, in all the half-dozen cases that I examined 

 concerning this. 



Comparing my description of Champia parvula with the description 

 of Lomentaria kaliformis by Nageli and Wille, there will be noticed 

 a striking similarity in general structure and in the details of growth, 

 so far as either Nageli or Wille describes them, except in regard to 

 the apical cell. Further investigation is necessary to explain this 

 remarkable difference in two species otherwise so much alike. 



In order to see if they might throw any light on my subject I have 

 made a hasty examination of some alcoholic material of Champia sali- 

 cornoides, Harv., from Key West, and of Lomentaria Baileyana. The 

 former has an apical growth identical with that in Champia parvula, 

 and does not differ very greatly in structure from that species. The 

 frond is much larger, but the individual cells are of about the same size. 

 The branches in Champia salicomoides do not come off at the nodes, 

 but may spring from any part of the internodes. At the base of each 

 brauch is a layer of cells smaller than those in the wall of the main 

 stem, but it is apparently a continuation of that structure. Then 



