REJUVENESCENCE IN NATURE. 141 



and the allied genus Bulbochcete, in which particular 

 cells, in (Edogonium those of the unbranched filament, in 

 Bulbocktfte those of the branches, swell up and produce 

 within a motionless seed-cell, acquiring a special mem- 

 brane, often quite removed from the membrane of the 

 mother-cell, and destined to a long stage of sleep, while 

 the contents of the rest of the cells, when otherwise 

 sufficiently abundant in quantity, become converted into 

 an active germ-cell, bearing a crown of numerous cilia. 

 In (Edogonium the birth of the swarming-cell takes place 

 through a transverse dehiscence of the parent- cell at the 

 anterior end; in Bulbochate by disarticulation of the 

 small cell bearing the bristle, and rupture of the wall 

 separating it from that of the large cell* Certain species 

 of (Edo(/onium ((E. echinospermum and apophysatum} are 

 especially remarkable, since they produce, in addition, 

 two kinds of swarming cells, macrogonidia and microgo- 

 nidia, the latter of which originate in special, very short 

 cells, arranged mostly in groups between the larger 

 cells. The macrogonidia germinate as soon as they come 

 to rest, and grow up into normal filaments ; but the 

 microgonidia, although they germinate, produce only 

 two-celled dwarfs, which die away without developing any 

 further. The genus Coleochate^ affords another example 

 of the united occurrence of gonidia and spores. Indi- 

 vidual terminal cells of this genus are developed into 



* In (Edogonium fonticola A. Br. (' Kg. Sp. Alg.,' p. 368), a species which 

 occurs almost every where in the pools formed by running springs, the forma- 

 tion of the " swarmers" may be observed throughout the whole year, while 

 the formation of the resting spores occurs but rarely. In (E. capillare, 

 the commonest species of the genus, I have hitherto met with "swarmers'' 

 alone. I have observed both kinds of fructification in (E. Landsboroughii 

 (Hass.), vesicatum (V&uch.),ff(sciatum (Hass.), Braunii, Kg., echinospermum, 

 A. Br. (Kg. 1. c. 366), apophysatum, A. Br. (ibid.), Bulbochcete setigera, Ag., 

 and minor, A. Br. (Kg. 1. c. 422). Cymatonema confervaceum, Kg. (Sp. Alg. 

 375), behaves exactly like (Edogonium in the bursting of the cells, but I have 

 not yet succeeded in observing the swarming out. (See also Thuret, 



' Zoospores des Algues,' Ann. des Sc. nat., 3d ser., xiv, p. 17, pi. 19. A.H.) 

 f Tide Nageli, ' Algensysteme,' p. 166, v, f. 22 31. I have observed 

 the formation of spores, as well as of gonidia, in both species of this genus, 



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