SECT. I 



CRYPTOGAMS 



341 



blue-green pigment (phycocyau) from ■which the name of the class is derived. The 

 product of assimilation is glj'cogen. The centre of the cell is occupied by the 

 colourless central body, which corresponds to a nucleus and contains chromosome- 

 like structures. As definite inclusions of the cells may be mentioned the 

 cyanophycin granules, which are of proteid nature and are situated within the 

 chromatophore. Chitin has been shown to be present in tlie cell wall. 



Reproduction is exclusively vegetative by cell division. In many ibrms resting 

 spores are formed by the enlargement of single aells, the walls of which become 

 greatly thickened (Fig. 253). Resting nuclei are present in these spores. 



Just as the Bacteria are designated Fission-Fungi (Schizomycetes), the Blue- 

 green Algae may be termed Fission-Algae (Schizo- 

 phyceae), since the reproduction of both depends 

 on fission. The two groups would form the class of 

 fission plants Schizophyta. The Bacteria and the 

 Cyanophyceae have much in common, but the cilia 

 and endospores of the former are unknown in the 

 latter group. According to the observations of 

 Philipps, which, however, rec^uire confirmation, 

 some of the Cyanophyceae which exhibit move- 

 ments possess cilia. 



The simplest Cyanophyceae consist of spherical 

 cells ; this is the case with species of Chroococcus. 

 In Gloeocapsa (Fig. 251), found on damp rocks and 

 walls, the cells remain connected together after 

 division into a gelatinous mass, foi-ming a multi- 

 cellular colony. 



The species of Oscillaria, which occur every- 

 where in water or on damp soil, are the simplest 

 of the filamentous forms. The filament, which is 

 usually provided with a thick sheath, consists of 

 similar flattened cells (Fig. 252). It can separate 

 into pieces (hormogonia), which become free owing 

 to the pressure of the sheath, and grow into new 

 filaments. In other filamentous Cyanophyceae speci- 

 ally modified cells with their contents degenerated 



occur in the filament. The significance of these heterogysts is not yet clear. 

 The species of Nost.oc (Fig. 253), whose bead-like filaments are united by the 

 swelling of the cell walls into more or less spherical gelatinous colonies living on 

 damp soil or in water, afi'ord an example of this. 



Some Cyanophyceae take part with the Fungi in the formation of Lichens. 

 Some species also are endophytic and inhabit cavities in other plants, e.g. 

 Anuhaena in AzoUa, Nostoc in some Liverworts, in Lcmna, and in the roots of 

 Cijcas and the stem of Gunnera. 



Fiii. 233. — Nostoc Linckii. A species 

 that floats freely in water. A, 

 Filament with two heterocysts 

 (/i) and a large number of spores 

 (sp) ; B, isolated spore beginning 

 to germinate ; C, young filament 

 developed from sjjore. (After 

 BOENET, X 650.) 



Class III 

 Flag-ellata (Flag-ellates) ('• ") 



The Flagellata are a group of unicellular, aquatic organisms exhibiting a wide 

 range of form ; they combine animal and vegetable characteristics, and may be 



