INTRODUCTION TO CEYPTOGAMIC BOTANY. 107 



iu the third division, which comprises a considerable number 

 of species which have not green fruit in any stage of growth ; 

 or at least not as a primitive stage, for the red spores of the 

 second order sometimes become green in decay. The contrary 

 effect takes place in some Chlorosperms, where the green 

 assumes a deep red, but not rosy tinge, probably by the same 

 process which changes the natural green of leaves into 

 autumnal red. This is not, however, the point to which I 

 allude ; there is a considerable number stiU of species of 

 Frotococcus, Hcematococcus, &c., which are essentially rose- 

 coloured. But this is merely one of those cases in which 

 the attributes of the superior order are indicated, as it were, 

 by the first elements. The shades of transition from HcBTna- 

 tococcus sanguineus, Ba/ngia atropurpurea, and Porphyra 

 (Fig. 27), the analogue of Nityphyllum, are certain, and it is 

 only an unwillingness to adopt colour as a generic character 

 which prevents such species from being dissociated. The cha- 

 racters by which Botrytis is held distinct from Chroolepus, axe 

 scarcely stronger, at least technically speaking. Naturally they 

 are as widely separated as the east from the west. In Batracho- 

 spermum, we see species possessing the true green of Chloro- 

 sperms and the rosy purple of Khodosperms ; and the red species 

 seem at first sight aUied to Glceocladew, the green to Chorda- 

 riacecB; there is, however, no close definition even of species, 

 though, to the eye, apparently so distinct, and the coloured indi- 

 viduals are, probably, mere analogues, and no proper denizens of 

 a higher order. In the tribe of Oscillatorice, there is frequently 

 a deep purple, and sometimes even a rosy red. The waters of 

 certain lakes, for instance, even at a distance, are red from the 

 diffusion of Lyngbya prolifica, Grev. Again, in the Dia- 

 tomacece there is seldom a grass-green colour, but rather a 

 yellow olive (lederbraun, as it is called by the Germans), some- 

 times approaching to a golden tint. Making allowance, then, 

 for a few exceptions, which, from the very nature of vegetable 

 productions, will occur in every systematic arrangement, the 

 following characters may be proposed : — 

 ]. Chlokosperme^. 

 For the most part green, but varying occasionally to olive. 



