336 



BOTANY 



This Alga possesses a brownish thallus, enveloped in mucilage, and consisting of 

 verticillately branched filaments. The sexual organs appear in the autumn and 



form on the branching whorls glomeruli 

 or spherical bodies composed of short, radi- 

 ating branches. 



The antheridia, also known as sperma- 

 tangia (Fig. 262, A), are produced, usually 

 in pairs, at the ends of the radiating 

 branches of a glomerulus. Each antheri- 

 dium consists of a single thin-walled cell, 

 in which the whole of the protoplasm, as 

 is the rule in all Hhodophyceae, is con- 

 sumed in the formation of one uninuclear 

 spebmatium. The spermatia are nearly 

 spherical, and immediately after their dis- 

 charge from the antheridia (A, o, s) are 

 naked, but afterwards become invested with 

 a thin outer membrane or cell wall. They 

 contain a single nucleus, and are non- 

 four extruded tetraspores. (After Thuhet. ) motile, like the ciliated spermatozoids of 



the other Algae, and have therefore re- 

 ceived a distinctive name. In consequence of their incapacity for independent 

 movement, they must be carried passively by the water to the female organs, which 

 are situated near the antheridia at the ends of other branches. The female organ 



Fig. 261. — CallitJutmnioncorymliosum. A, Closed 

 sporangium ; B, empty sporangium with 



Fig. 262.— Batmdlwsperrmnn moidHformc. A, Male branch with antheridia, isolated by pressure ; 

 s*, a spermatium ; s, a spermatium escaping from an antheridium ; v, an empty antheridium. 

 B, female branch with an unfertilised carpogonium ; c , basal portion ; t, triehogyne of cavpo- 

 gonium. C, female branch with fertilised carpogonium ; s, the spermatium after the fusion 

 of its contents with the triehogyne ; c, fertile filaments developing from the basal portion 

 of the carpogonium. (X 540.) 



is called a carpogonium: (Fig. 262, B), and consists of an elongated cell with a basal, 

 flask-shaped portion (c) prolonged into a filament, termed the triohogyne (<). The 

 basal portion contains the egg, which is provided with a large nucleus and chro- 



