194 



ALG.E 



(Harv.), and some others, the 'phyllotaxis' is spiral. The genera Ryti- 

 phloea (Ag.), Vidalia (Lmx.), Amansia (Lmx.), and Polyzonia (Suhr) 

 are distinguished by the endogenous formation of the normal lateral 

 shoots. In Pollexfenia (Harv.) and allied genera, Falkenberg records a 

 remarkable congenital union of all the branches of the thallus which lie 

 in the same plane. 



The red colouring matter of the Floridese has been investigated 

 by Rosanoff, Cramer, Askenasy, Sorby, and others. 

 Cramer first extracted it, from Bornetia secundiflora 

 (Ag.) and Callithamnion caudatum (Ag.), in the form 

 of regular crystals, partly hexagonal, partly octohedral, 

 and gave it the name rhodospen?iin. Rosanoff ex- 

 tracted it by cold fresh water, and found it carmine- 

 red in transmitted, reddish yellow, or rarely green, 

 in reflected light. It is insoluble in alcohol. The 

 chlorophyll-grains also exhibit fluorescence when left 

 behind, if the pigment, tho: phyco-erythrin of Askenasy 

 and Sorby, has escaped from them in consequence of 

 injury to the plant. The spectrum of the chloro- 

 phyll is nearly identical with that in Flowering Plants. 

 The compound pigment of the red Algae is termed 

 by Schiitt rhodophyll, the term phyco-erythrin being 

 limited to the portion soluble in water, while the 

 portion soluble in alcohol he calls Flo- 

 ^ ridece-green. Cohn found, in Bornetia 



(Thur.), colourless crystalloids of an albu- 

 minous substance coloured a beautiful 

 red by the same pigment ; and Klein 

 has found similar crystalloids in several 

 Floridese. The chromatophores contain 

 starch-grains, which differ both from 

 the ordinary grains of Flowering Plants 

 and from those of the brown Algae in 

 being coloured brown or red by iodine. 

 Schmitz (Sitzber. Niederrhein. Gesell., 

 1880) has detected a number of nuclei in the vegetative cells of many 

 Floridese, but not in the reproductive cells. Hick (Proc. Brit. Ass., 1883; 

 ' Nature,' vol. xxix., 1884, p. 581), Massee (I.e.), and Moore (Journ. Linn. 

 Soc. Bot., vol. xxi., 1886, p. 595) find continuity of protoplasm from cell 

 to cell very beautifully displayed in Callithamnion (Lyng.), Ptilota (Ag.), 

 Polysiphonia, and several other genera, not only in the vegetative cells, 

 but also in the tetrasporanges. In Corallina (L.), Melobesia, Liagora 



Fig. 171. — Hydrolapathiim sangui- 

 neHt7i Stackh. a, two young fronds 

 with two cj-stocarps ; b, c, prolifica- 

 tions from the stem (natural size). 

 (After Kiitzing.) 



