ON THE GEEMmATION OF CHAEA. 301 



oospores capable of genninating, with a thinner, lighter, almost 

 colourless shell. Concerning the more minute structure of the ligni- 

 fied membrane, I will content myself here with observing that, 

 according to the species, I invariably found the surface homogeneous 

 and smooth, as in Tohjpella glomerata, Nit. hyalina, and C. crinita, 

 or net-like, and pitted as in N. capitata and mucronata. 



In many species the shell is solely composed of the lignified 

 membrane ; thus, for instance, in C. scoparia, crinita, N. mucronata, 

 capitata, tenuissima, and Tohjpella glomerata (fig. 18): in others, as in 

 C. foetida (figs. 1 and 2), fragilis, contraria, harlata, and Tolypella 

 intricata (figs. 11 and 13), it is densely overlaid with a more or less 

 thick layer, consisting of granules of carbonate of lime ; hence it may 

 be called the chalk shell. Such shells are opaque, and exhibit a dull 

 grey or white surface in reflected light. If this salt be carefully 

 dissolved with an acid it will be seen that it is deposited on a soft 

 hyaline membrane which completely invests the lignified coat. In 

 C. fragilis, where it is rather thick, and particularly in C. harlata^ 

 where it almost fills the whole of the interior of the former investing 

 tubes, this membrane shows a copious tender stratification after the 

 carbonate of lime has been dissolved. To investigate the first stages 

 of germination, it is necessary to remove the chalk. 



I have observed germination in C. fcetida, A. 'Qv., fragilis, Desv., 

 contraria, A. Br., crinita, Wallr., scoparia, Bauer, Tolypella intricata^ 

 Eoth, glomerata, Desv., Nitella capitata, A. Br., tenuissima, Desv., 

 hyalina, A. Br., and so far followed it up in these species* as to be able 

 to say that, with the exception of trifling diflferences in shape, its 

 phases are exactly the same in all. The same applies to the following 

 additional species examined by Nordstedt : Nit. flexilis, Ag., N. mu- 

 cronata, A. Br., Tolypella nidifica, A. Br., and Lychnothamnus 

 Wallrothii, Eupr. The Nitellas, Tolypellas, and especially the widely 

 dispersed, freely germinating Chara foetida, are the best for examina- 

 tion. 



The commencement of germination is marked by the reflux of the 

 coarse-granuled fat and starch contents from the crown end of the 

 oospore to make room for an accumulation of light-coloured fine-grained 

 protoplasm. This completely fills the crown end, and it is of the 

 shape of a plano-convex lens, of which^the greatest thickness is about 

 equal to the distance between two of the spiral bands of the shell. 

 Its flat boundary surface abuts closely on the fat and starch filling the 

 remaining space of the oospore. At the boundary point a partition is 

 quickly formed, separating the space filled with protoplasm at the 

 crown end, as a small lens-shaped cell, from the larger cavity filled 

 with reserve substance. (Figs. 1, 2, 3, and 11.) The latter may be 

 termed the basal cell, and the former lens-shaped one the nodal cell. 

 All further morphological changes in the development of the germi- 

 nating plant proceed from the nodal cell. This at first grows very 

 little either in height or breadth, and without any essential alteration 

 in its shape, but sujBficiently to burst the 5 angled crown into five 



* The nomenclature adopted throughout is that of A. Braun's *♦ Conspectus 

 Systematicus Characearum Europearum," 1867. 



