MARINE ALG^!. 



273 



united in a bunch as in Grijfithsia, 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 

 epiral 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 011 the 

 bifurcations of the terminal branches. Are not these spiral 

 filaments closely allied to Oscillatoriacece ? The spores are 

 simpler structures than the tetraspores, and mostly occupy 

 a more important posi- 

 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 T 

 conceptacle ; such a fruit 

 is called a favellidium, 

 and occurs in Haly- 



menia; the same name Flg - i50.-cflerio diploma. Section of 

 is applied to the fruits 

 oi 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 



T 



lacinia of a frond, showing the stalked ijrW 

 chambered oosporangeff, growing on tufts 

 with intercalated filaments. Magnified 50 

 diameters. 



