HICKS, ()\ THE DIAMOIIPHOSIS OF LYNGBYA, KTC. 161 



edges of the wavy frond, the cells, by the solution of the in- 

 tercellular substance, become free, still preserving the tendency 

 to segment, so that by generating the bin aryov quaternary form, 

 they pass tlirough changes which belong to the gonidia derived 

 from the linear form (Lyngbya), and, like them, form one of the 

 groups, classed hitherto as PalmellacecC (fig 12 a). In some 

 of them the cell-wall is w^ell marked, the contents arranging 

 themselves in a crucial manner, apparently indicating the 

 future segmentation (fig. 12 b). Whether these revert through 

 minute subdivision to the linear form, as I have already de- 

 scribed in the Lyngbya (fig. 4a), I am not able to say; but 

 in their maturity they have a very strong tendency to undergo 

 the linear form of segmentation — at fig. 14 the cells about to 

 become free are shown in this state ; some are already free 

 and proceeding on to Lyngbya rapidly, while others are still 

 attached to the margin of the frond. But this condition is 

 not confined to its edge. I have seen the whole of the cells 

 of a large portion still in position, having taken on this 

 action to the extent of four or five cells. Considerable 

 variety is shown in this process, and it is seldom that 

 one part of every frond does not show some indication of 

 it. That these threads pass to Lyngbya can be observed 

 very readily. 



Thus it will be remarked that a constant struggle is 

 going on between the linear and lateral mode of growth; 

 and between either of these, and the gonidial, with its 

 changes; the balance seeming to be always uncertainly 

 suspended between them. This power of the cells of the 

 wavy frond to assume the linear growth should be com- 

 pared with the similar condition seen in the cells of the 

 Lyngbya, which I have drawn at fig. 16, under various 

 aspects. The gonidia remaining within the tube, but more 

 or less distinct from each other, have changed in precisely 

 the same manner as shown at fig. 14. 



There are some other conditions of the growth of the 

 cells of Lyngbya, shown at fig. 17. The state indicated at 

 a appears to be similar to mother-cells ; the large green 

 cell becomes free, and, I believe, gives rise to numerous 

 small cells. In fig. 17 b the gonidia have segmented, and 

 each division has increased, possibly to form mother-cells. 

 Thus I have pointed out a series of existences : 



1. The mature Lyngbya. 



2. Its gonidia and their segmentation. 



3. Their recurrence to Lyngbya. 



4. The lateral segmentation of the cell of Lyngbya, in part 

 or wholly, passing ultimately to the formation of broad. 



