REJUVENESCENCE IN NATURE. 183 



time a " s warming-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 whole, or divided, 

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

 course of life; the cells coming to light 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 Sderococcus* 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 Coleochtete scutata (vide supra, p. 141) ; by a 

 lateral splitting of the cells of a shrubbily-branched thallus 

 in Coleockate pulvinata (p. 142), Chfstophora, Stigeodo- 

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

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

 162) ; by disarticulation of the laterally attached bristle- 

 cells and breaking-open of the septa separating them from 

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

 single resting cell is set free from its coat (theperispore), 

 and this by dehiscence at the apex, in Chantransia 

 (p. 143), Chroolepus (?), and the Fucoidea3 in the extended 

 sense, t Two active germ -cells slip out from a mother- 

 cell, breaking through it laterally, in Ulothrix Braunii 



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

 cilia, like the allied genera Cfuetophora, Stigeoclonimn, &c. 



t Alga pycnospermece et angiospermete, Kiitzing. In regard to the exist- 

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

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

 in Fucus nodosus and serratus, ('Ann. des Sc. nat.,' 18i5, t. i, c, f. 21, and 

 t. ii, f. 32). 



