MARINE ALG.E. 



273 



united in a bunch as in Griffithsia, or enclosed in a trans- 

 parent cylinder, as in Polysiphonia, or covering a kind of ex- 

 panded disc of peculiar form, as in Laurencia." According 

 to competent observers, these cellules contain spermatozoids. 

 Nageli describes the spermatozoid as a spiral fibre, which, as 

 it escapes, lengthens itself in the form of a screw. Thuret 

 does not coincide in this view ; on the contrary, he says 

 that the contents are granular, and offer no trace of a 

 spiral filament, but are expelled from the cells by a slow 

 motion. The antheridia appear in their most simple form 

 in Callithamnion, being reduced to a mass of cells com- 

 posed of numerous little bunches which are sessile on the 

 bifurcations of the terminal branches. Are not these spiral 

 filaments closely allied to Oscillatoriacece 1 The spores are 

 simpler structures than the tetraspores, and mostly occupy 

 a more important jDOsi- 

 tion. They are not scat- 

 tered through the frond, 

 but grouped in definite 

 masses, and generally 

 enclosed in a special 

 capsule or conceptacle, 

 which may be mistaken 

 for a tetraspore case. 

 The simplest form of 

 the spore fruit consists 

 of spherical masses of 

 spores attached to the 

 wall of the frond, or 

 imbedded in its sub- 

 stance, without a prope" 

 conceptacle ; such a fruit 

 is called a favellidium, 

 and occurs in Haly- 

 raenia ; the same name 

 is applied to the fruits 

 of similar structures not 

 perfectly immersed,, as 



those of Gigartina, Gelidium, &c, where they form tuber- 

 cular swellings on the lobes. In some, the tubercles pre- 

 sent a pore at the summit, through which the spores find 



Fig. 150. — Cutleria dichotoma. Section of a 

 lucinia of a frond, showing the stalked eight 

 chambered oosporanges growing on tufts 

 with intercalated hairs Magnified 50 dia- 

 meters. 



