288 



THALLOPHVTES. 



the cortical layer (r) of the carpogonium commences ; out of the cells that support it 

 proceed branches {A, og") which cling closely to it. These again form branches which 

 also cling closely and divide transversely ; the branchlets of other branches also ramify 

 ( J3) ; and only the neck of the carpogonium does not become covered with the cortical 

 layer. All this happens between May and July; later, the contents of the remaining cells 

 of the plant disappear, and the walls of the cortical layer of the carpogonium assume 

 a deep dark-brown colour. The further development of the oospore within the carpo- 

 gonium now covered with its cortical layer begins only in the next spring; a paren- 

 chymatous tissue is formed by successive bipartitions ; the cortical layer splits and is 



Fig. 187. — A part of fertile thallus of Coleochate fulvinata (X350); i? ripe carpogonium enclosed in its cortical layer; 

 C germinating sporocarp, in the cells of which the zoospores are formed ; D zoospores (B—D X 280, after Pringsheini). 



thrown off (Fig. 187, C) ; and from each cell arises a zoospore, and from this again an 

 asexual plant. C. scutata (the most abnormal species) deviates from these processes 

 only so far that in it the carpogonia provided with their cortical layer lie on the surface 

 of the disc, and the antheridia are the result of divisions of disc-cells into fours. 



Pringsheim {loc, cit.) has already pointed out various relationships existing between 

 the Coleochsetese, the Florideae, and the Gharaceae. 



B. The Floride^. 



The carpogonium is either unicellular or composed of several cells, and it is provided 

 with a permanently-closed trichogyne. If the carpogonium is multicellular, the tri- 

 chogyne is borne by a lateral row of cells, which is termed the trichophore. Fertilisation 

 is effected by non-motile rounded antherozoids which become attached to the trichogyne. 

 As a consequence of fertilisation the basal portion of the carpogonium, which does not 

 form the trichophore, forms a great number of spores by budding, each spore being the 

 terminal cell of a short branch. The mass of spores is usually surrounded by an invest- 

 ment and thus a cystocarp is formed. 



The Florideae^ are a group of Algae of extraordinarily variable form, belonging. 



^ Nageli und Cramer, Pflanzenphys. Unters. Zurich, Heft I. 1855; Heft IV. 1857. — Thuret, 

 Ann. des Sci. Nat. 1855, Recherches sur la fecondation, &c. — Pringsheim, Ueber die Befruchtg. u. 

 Keimung der Algen, Berlin 1855. — [Quart. Journ. Micr. Sc. 1856, vol. IV. pp. 63, 124.] — Nageli, 



