164 THE PHENOMENON OF 



with chlorophyll and starch vesicles, which, in the 

 earlier vegetative period of the cell, form a lining of 

 the wall, retreat from this membrane, and present 

 themselves as a new, everywhere free cell destined for 

 reproduction. The cell-body thus detached from the 

 walls, appearing in a new form, with a new vital direc- 

 tion, presents itself with regular form and boundaries, 

 before a trace of the cell-membrane subsequently clothing 

 it is visible. It mostly assumes a perfectly globular 

 form, even when the mother-cell is longish ;* in this first 

 period of formation its surface appears somewhat uneven 

 from the projection of chlorophyll-vesicles ; the whole 

 internal cavity is filled up, and of deep green colour. 

 Very slowly and gradually there appears, first a simple, 

 afterward a double, and sometimes even a triple-layered 

 membrane upon the surface, while the chlorophyll and 

 starch formations in the contents progressively vanish, and 

 give place to reddish oil-drops, which at length occupy 

 nearly the whole cavity, and give the seed-cell a brownish- 

 red, sometimes even a red-lead coloured appearance. The 

 seed-cells of the Zygnemacea originate in the same way 

 as those of CEdogonimn, with the single distinction that 

 in the former the contents of two chambers become united 

 to form one seed-cell.f The formation of the cell-mem- 

 brane, succeeding the shaping out and limitation of the 

 cell, as a secondary phenomenon, may be well observed 

 also in Sph(Broplea.\ The links of this Conferva are of 

 unusual length, 10 — 20 times as long as broad. The 

 distribution of the contents is extremely elegant, and 

 allows, in some measure, of a comparison with that in 

 Spiroggra, with this difference, however, that the chloro- 

 phyll forms, not spiral, but annular bands, 20 or 30 



* Thus especially in QMogotimm Lamlshoroughii, Hassall. 



t Vide Nageli, 'Ueber freie Zoll-bildung.' ' Zeitsclirift/ 1847, p. 27. 

 (Transl. in Kay Society's publications, 1849, p. 98.) 



% My observations on tbis remarkable genus of Algee were made in the 

 autumn of 1847, on Sphrdroplea BruKini, Kz., ('Sp. Alg.,' 462.) (Vide also 

 Fresenius, ' Sphar. aiiiiiilina,' ' Bot. Zeitung.,' 1851, vol.] ix, 241. 

 —A. H.) 



