302 THE PHENOMENON OF 



only less striking alternation, of more richly filled and 

 poorer, darker and lighter cells, occurs also in the sterile 

 or merely gonidium-bearing filaments of most of the 

 (Edogonia ; in those species, moreover, which have the for- 

 mation of microgonidia mentioned above,* the longer cell 

 which precedes every group of the short cells in which 

 the small swarm ers are formed, is found poor in contents, 

 like the ante-cell of the mother-cell of the spore. None 

 of these phenomena can be explained by a subsequent 

 wandering of the cell-contents, produced by union of 

 previously separate cells, but are all caused by the distri- 

 bution of the contents in the very formation of the cells. 

 For in QHdogonium occur secondary processes of cell- 

 formation in the filaments, possessing the peculiarity 

 that the individual cells of the filament divide, not into 

 like, but more or less strikingly unlike cells, and in such 

 a way that the upper of the two cells produced by divi- 

 sion is the shorter and richer in contents, the lower the 

 longer and poorer in contents. The difference of the 

 two sister-cells is slighter in filaments or fragments of 

 filaments remaining sterile, as also in those in which 

 merely macrogonidia are to be formed, and it is mostly 

 very striking, on the other hand, where the formation of 

 spores (or microgonidia) is to take place. The anterior 

 shorter cell, filled with more concentrated contents, 

 becomes, in this case, the mother-cell of the spore. This 

 process of cell-formationj division into unlike halves, is 

 frequently repeated in the lower ceH, this again dividing 

 into a shorter, fuller, upper, and a longer, lower cell, &c. 

 Thus, in sporiferous filaments, a second, third, and fourth 

 spore mother-cell may be added successively to the first. 

 The same is exhibited in the formation of microgonidia, 

 wherein I have seen the number of short mother-cells of 



* (Edogonium echinospermum and apophysatum. See p. 141. The nu- 

 merous, closely superstratifled little cells, which Le Clero, 1. c, f. 9, figures 

 between the larger cells, in a filament supposed to belong to ProUfera 

 rivularis, {(Edogon. LandsboroiigMi,) and in the explanation of the plate 

 takes for spiral-filaments, are doubtless emptied mother-cells of microgonidia. 

 (See Thuret.) 



