142 



RESEARCHES QN FUNGI 



(c/. Fig. 79). Notwithstanding that algologists in general^ hold 

 the view that a Volvox is a colony of cells, the writer, with Janet,^ 

 is inchned to regard a Volvox as a highly organised, multicellular 

 individual plant. In support of this view it may be said : ( 1 ) that 

 the cells of which a Volvox is composed are all derived by cell- 

 division from one and the same mother-cell ; (2) that the units of 



Fio. 74. — Aphanocapsa Grevillei, 

 a simple colonial Blue-green 

 Alga. The cells are globose 

 and aggregated to form a 

 small colony within a com- 

 mon homogeneous gela- 

 tinous integument. Found 

 in Yorkshire, England, and 

 drawn by G. S. West. From 

 his British Freshwater Algae 

 (1904). Magnification, 450. 



Fig. 75. — Colonial Blue-green Algae, in which the 

 individual cells are held together in a mass of 

 mucus. A, Coelosphaerium Kiitzingianum from 

 Loch Neagh in Ireland : the cells are arranged 

 just within the periphery of a spherical mass 

 of mucus. B, Gomphosphaeria aponina, from 

 Keston Common, Kent, England : the cells are 

 fewer and more scattered, pyriform in shape, 

 arranged in pairs, and are disposed chiefly toward 

 the periphery of the mass of mucus. Found and 

 drawn by G. S. West. From his British Fresh- 

 water Algae (1904). Magnification, 350. 



the cell-mass never live an independent life but are in contact with 

 one another from the first ; and (3) that the cell-mass, from an 

 early stage of development, is united into one whole by means of 



1 E.g. F. Oltmanns, Morphologie und Biologie der Algen, Jena, 1923, p. 56. 

 F. E. Fritsch in his revision of G. S. West's British Fresh-ivater Algae (Cambridge, 

 1927, p. 26) says, in respect to Volvox, " such colonial forms are scarcely to be dis- 

 tinguished from multicellular individuals," but he does not tell us how Volvox 

 diflEers from a multicellular individual. 



2 C. Janet, Le Volvox, Limoges, 1912, pp. 12, 16, 17. In treating of the phylogeny 

 of Volvox, Janet says that, at one stage in evolution : " D'individus, les Flagellates 

 sont devenus des plastids constitutifs d'une association definitive, et la colonic est 

 devenue un individu." 



