180 THE PHENOMENON OF 



paraphyses) originate by similar elevation and division of 

 the cortical cells, which, hovpever, is repeated several 

 times. The cuticle, at the same time, is incapable of 

 sharing in this development of the cortical cells ; it is 

 separated from the sorus as a connected pellicle, pushed 

 upvFard, torn up at one side and thrown over, so that it 

 looks not unlike the indusium of an Asplenium. 



2. The complete skinning of the cell, the real peehng 

 off of an -outer cell-membrane, while the inner follows 

 the new development of the contents, is displayed in the 

 germination of the Mosses* and Ferns jf it doubtless 

 occurs also in the germination of all the thick-coated 

 spores of Algse, when they awaken from the stage of rest. 

 It was seen by Vaucher in the Zygnemaceae,J and 

 according to my own researches (already mentioned 

 above, p. 135) it is double in Spirogyra,kj for two mem- 

 branes are stripped off in succession. The strange 

 skinning of the newly-formed spores of Sphmroplea has 

 also been mentioned (p. 166). And the peculiar manner 

 in which the spore of Equisetum frees itself from its 

 mother-cell membrane, splitting into two right-wound 

 spiral bands, || may be called a skinning. But we find 

 skinning of the cells connected not unfrequently with the 

 vegetative development and multiplication of the cells by 

 division, among the Unicellular Algse. The stripping off of 

 the mother-cell membrane connected with the multiplying 

 division of many Desmidiacese, was described and figured 

 by Focke^ in Closterium Trabecula. The cell-membrane 



Kz., ^^ germ-cell," {Jceim-zelle,) Wii^.) ; but Decaisne, (' Classif. des Algues,' 

 p. 26,) states distinctly that the spores escape from it by rupture, while it 

 remains behind upoa the thallus as an empty perispore. 



* W. P. Schimper, ' Kecherohes sur les Mousses,' t. i. 



t Leszozyo-Suminski, ' Zur Bntwicklungsges. der Parrenkrauter,' (1848,) 

 t. i. 



I Vaucher, ' Hist, des Conferves d'Bau douce,' t. iv, f. 5 ; t. vi, f. 4. 



§ (See Pringsheim, Transl, from the 'Flora,' in 'Annals of Nat. Hist.,' 

 2d ser., vol. xi, p. 310.— A. H.) 



II Mohl, (' Flora,' 1833, p. 45, and ' Verm. Sohrift.,' p. 72, t. ii, figs. 6, 7), 

 represents these bands as left-wound, an error which probably arose from 

 neglecting the use of the mirror in the first lithographing. 



f' Pooke, 'Phys. Studien.,' p. 73, t. iii, f. xvii. According to Ralfs, 



