96 VEGETABLE CELLS. 



acquired sufficient size, we recognise an enveloping mem- 

 brane and inclosed contents. 



In Chlorococcus, Grev., and Htemato coccus, Ag., the new 

 cells appear as green (in the former genus) or red (in the 

 latter) globules, in which we only perceive a definite out- 

 line. When they leave the parent-cell and become larger, 

 we distinguish a colourless membrane inclosing coloured 

 contents. I have never been able to detect any sign of a 

 nucleus. It appears as if merely small isolated portions 

 of the contents became agglomerated, assumed a perfectly 

 spherical form, and produced a membranous coat. The 

 rest of the contents of the parent-cell are gradually dis- 

 solved. 



Valonia utricularis, Ag., consists of one large cell. On 

 the inner surface of its membrane lies the mucilaginous 

 layer. The germ-cells (Keimzellen) originate in this. At 

 first they have the appearance of minute drops of mucilage. 

 The membrane cannot be detected until they have become 

 larger, granular, and green.* 



The origin of the germ-cells (spores) in the thecse of 

 Fungi and Lichens is accompanied by the same phe- 

 nomena. At first they present themselves, sometimes in 

 the form of homogeneous drops of mucilage, sometimes 

 as little hollow globules, the former in clear, diluted, the 

 latter in dense, mucilaginous, cell-contents of the theca. 

 In both cases the nascent spore-cell originally exhibits 

 only a definite outline, and a distinct membrane only at 

 a subsequent epoch, f No nucleus is visible in these ; at 

 a later period, when the cell has increased in size, and 

 the contents have become transformed, a nucleus is seen 

 in some instances. 



In Coleochcete scutata, Breb., the germ-cells appear in 

 the parent-cells, at first as little green, homogeneous glo- 

 bules, on which a membrane afterwards becomes visible. 

 A nucleus may sometimes be detected in the fully-de- 



* For a more minute account, see Nageli's New System of Algae. (Die 

 Neuen Algen-systeme, &c. Zurich, 1847.) 

 f See Nageli, Linnrea, 1842, p. 257, PL ix, figs. 32, 34, 41, 45. 



