REJUVENliSCENCE IN NATURE. 183 



time a " swarming-out/' in which the peculiar motion 

 begins sometimes during the birth, or even before the 

 birth, inside the parent envelope. The orifice in the 

 mother-cell membrane, as in " skinning," may be either 

 an irregular rupture or a regular dehiscence. The con- 

 tents left in the old coat are either undivided, entering 

 upon their altered destination as a vi^hole, or divided, 

 i. e. separating into several cells in the transition to a nevp 

 course of life; the cells coming to hght are sometimes naked 

 gonidia, sometimes spores already clothed with a new 

 cell-membrane. We have already had cause to examine, 

 in detail, many of the examples to be cited here, so that 

 it suffices merely to recall them to recollection. A single 

 active germ-cell frees itself from its chamber by dehis- 

 cence of the latter at the apex in Vaucheria {vide supra, 

 p. 163); in Gongrosira Sclerococcus* by tearing at the 

 apex or the side, according as the mother-cell is an 

 apical-cell or a link-cell ; by bursting of the back- wall of 

 the cells of the circular thallus adherent by its lower 

 surface, in Coleochcete scutata {vide supra, p. 141) ; by a 

 lateral splitting of the cells of a shrubbily-branched thallus 

 in Coleocheste pulvinata (p. 142), CJiatophora, Stigeoclo- 

 nium, and Draparnaldia (p. 138) ; by annular dehiscence 

 at the upper end of the cells in CEdogonium (pp. 141 and 

 162) ; by disarticulation of the laterally attached bristle- 

 cells and breaking-open of the septa separating them from 

 tlie link-cell of the filament in Bulhochcete (p. 141). A 

 single resting cell is set free from its coat {i\ieperispore), 

 and this by dehiscence at the apex, in Chantransia 

 (p. 143), Chroolepus (?), and the Fucoidese in the extended 

 sense. f Two active germ -cells slip out from a mother- 

 cell, breaking through it laterally, in Ulothrix Braunii 



* Observed in July, 1847. The almost globular gonidia possess four 

 cilia, like the allied genera Chatophora, Sligeochnium, &c. 



t Alga pycnospermea et angiospermeee, Kiitzing. Iq regard to the exist- 

 ence of a perispore, vide the observations on Zonaria, p. 179. Decaisne and 

 Thuret also figure perispores visible even after the slipping out of the spores 

 in F'ucus noAosus and serratus, ('Ann. des So. nat.,' 1845, t.i, c, f. 21, and 

 t. ii, f. 32). 



