SCHIZOPHYTA. 21 



Swarm-cells, such as those of the higher Thallophytes, are found only in 

 Merismopcdia, a genus of Cyanophyceae, and perhaps in some other Chroococcaceae ; 

 but many Schizophytes possess the power of motion ; they swim hither and thither, 

 or the chains of cells which are spirally coiled turn on their own axis, or they can 

 bend to either side, or they exhibit other movements. 



The Schizophytes have no sexual organs. They multiply, as has been stated, 

 either by division into two of isolated cells, or where the species form chains of cells, 

 these break up into pieces, which have the power of motion and grow into new 

 individuals. Besides this both Cyanophyceae and Schizomycetes have resiing-cells, 

 isolated cells which have passed into a quiescent state, in which they may become 

 dried up without losing their vitality. These resting-cells are usually distinguished by 

 a thicker cell-wall and denser protoplasm, especially in the Cyanophyceae ; the resting- 

 cells of the Schizomycetes are very minute, and their structure therefore very difficult 

 to determine. (See below.) 



The Schizophyta then consist of the two following divisions : 



A. Cyanophyceae. 



B. Schizomycetes. 



A. CYANOPHYCEAE. 



The Cyanophyceae 1 (Phycochromaceae) are of a bluish or verdigris green, 

 or of some similar colour, due to a mixture of true chlorophyll and phycocyan, 

 which latter, when diffused out of dead or ruptured cells, produces the blue stain on 

 the paper on which filaments of OsciUatoria have been dried. Phycocyan, when 

 extracted with cold water from crushed plants, gives a solution which is a beautiful 

 blue in transmitted light, blood-red in reflected light 2 . If the crushed plants are 

 heated with strong alcohol after the extraction of the colouring matter, a green 

 solution is obtained which contains true chlorophyll and probably a special pigment, 

 phycoxanthin*. The cells of the Cyanophyceae, according to Schmitz 4 , have no 

 nucleus; but there are granules distributed in the protoplasm which are probably 

 composed of nuclear substance (nuclein). Propagation is entirely asexual, either by 

 resting cells, isolated cells rich in protoplasm, which secrete a thicker cell-wall and 



1 Nageli, Einzellige Algen, Zurich 1 849. Fischer, Beitrage zur Kenntniss der Nostocaceen 

 (Bern 1853). De Bary, Beitrag zur Kenntniss der Nostocaceen, insbesondere der Rivularien (Flora 

 !863). Bornet et Thuret, Notes algologiques, Fasc. I, II, Paris 1876 and 1880. Janczewski, Observ. 

 sur la reprod. de quelques Nostochacees (Ann. d. sc. nat. 5 ser. T. XIX). [Id. Godlewskia, n. g. 

 d'Algues de 1'ordre Cryptophycees (Ann. sc. nat. 6th ser. XVI. (1883).] Borzi, Note alia mor- 

 fologia e biologia delle alghe Ficocromacee (Nuovo giorn. bot. Italiano, Vols. X and XI). 

 [Falkenberg, Die Algen im weitesten Sinne, in Vol. II. of Schenk's Handb. d. Botanik. Tangl, Zur 

 Morphologic der Cyanophyceen (Sitz. d. k. Akad. d. Wiss. in Wien, Mai 1883). Zopf, Weit. Stiitze 

 f. meine Theorie v. d. Inconstanz d. Spaltalgen (Phycochromaceen) (Ber. Deut. bot. Ges. 1883). 

 Cooke, Brit. Freshwater Algae. Hansgirg, Ueber den polymorphism^ der Algen (Bot. Centralbl. 

 1885)]. 



2 Cohn in Archiv f. mikrosk. Anatomic v. Schulze, III. p. 1 2, and Askenasy in Bot. Zeit. 

 1867, Nr. 29. 



8 Millardetu. Kraus in Comptes rendus, LXVI. p. 505. 



4 Unters. liber die Struktur des Protoplasmas und der Zellkerne der Pflanzenzellen (Sitzungsber. 

 der niederrh. Gesellsch. 13 Juli 1880). [Hansgirg, Ein Beitr. z.d. Kenntn. d. Verbreitung d. Chroma- 

 tophoren und Zellkerne bei d. Schizophyceen (Ber. Deut. bot. Ges. 1885).] 



