ALGJE. 



443 



the contents are converted into a number of globular bodies, in others 

 the contents are developed into numerous spermatozoids. When mature, 

 orifices are formed in walls of the cells of both kinds ; the spermatozoids 

 escape from their parent cell, and make their way in through the orifices 

 of the parent cells of the spores ; the latter when fertilized produce their 

 cellulose coat and ripen to resting-spores, which are set free by the decay 

 of. the parent filaments. 



Analogous phenomena have been recently observed in various other 

 filamentous Confervoids, as in CEdoyonium, Bulbochcete ; and Cohn has 

 described a similar process in Volvox. 



The mode of fertilization in the Florideas, or Red Seaweeds, has been 

 well made out by MM. Thuret and Bornet, who thus describe the process 

 in Helminthora. A small cell, originating on the side of one of the 

 dichotomous filaments of which the frond is composed, elongates, divides 

 transversely, and becomes a short branchlet made up of four superposed 

 cells, of which the uppermost alone continues to develop. Shortly 

 there may be seen projecting from the summit of this uppermost division 

 a little protuberance, which gradually lengthens into a long hyaline hair, 

 often dilated at the extremity. This is the trichogyne or essential organ of 

 fertilization. When the spermatozoids (here globular and motionless) 

 come into contact with the upper part of this hair they adhere to it. 

 Then the cell which forms the base of the trichogyne swells and divides 

 into segments, and is soon transformed into a small cellular mass, which 

 gradually forms the young " cystocarp " or mass of spores. The trichogyne 

 gradually disappears. In Callitkam- 



nion the aggregations of spores called Fig. 507. 



favellce are formed from the side, 

 not at the base, of the trichogyne, 

 in consequence of fecundation by the 

 antherozoid. Here, then, we have 

 motionless antherozoids formed in 

 the antheridium of One plant, escap- 

 ing and coming into contact with 

 the free end or style-like process of 

 another plant; and, as a result of 

 this contact, the cell at the base 

 divides and subdivides into a mass 

 of spores. 



The observations made by Thuret 

 on Fucaceoe are very decisive. In 

 this Order the conceptacles produce 

 in their interior bodies of two kinds, 

 antheridia (fig. 511, c) and spore- 

 sacs (fig. 511, e), either together Or in Development and fertilization of spores of 



separate conceptacles (monoecious), 

 or in separate plants. The anthe- 

 ridia discharge 2-ciliated spermato- 

 Z'nds (fig. 511, d), which are poured 

 out through the pores of the recep- 

 tacles (fig. 511, a) into the surrounding water. At the same time the 

 spore-sac (fig. 511, e) bursts and emits an inner sac (fig. 507, a), in which 

 may be observed 2, 4, or 8 (a) spherical corpuscles, destitute of a cellulose 

 membrane ; this inner sac breaking loose, bursts and discharges its cor- 



fucus vesiculosus : a, inner spore-sac burst- 

 ing from the outer sac and about to liberate 

 the spores ; 6, a free spore (devoid of cellu- 

 lose coat) surrounded by spermatozoids ; c, 

 impregnated spore with a cellulose coat ; d, 

 the same germinating. Magn. 160 diameters. 



