920 VIII. CHARACEiK. 



granules on this fluid. Amici attributed them to electric action. Becquerel and 

 Dutrochet opposed this view. Donne, having observed that the green granules, if 

 detached from the tube which they line, and removed to one of the bands where the 

 current is not felt, execute a rapid rotatory motion, attributes the movement im- 

 parted to the liquid to the rotation of the granules ; and as no trace of vibrating 

 hairs has been discovered in these granules, Brongniart was led to suppose that the 

 ambient fluid is set in motion by successive contractions of the various parts of each 

 granule, that is to say, by a change of form analogous to a sort of peristaltic motion. 

 The BRANCHES are whorled on a level with the. joints ; they may be simple and bear 

 along their inner surface the reproductive organs, furnished with an involucre of 

 branchlets or bracts ; or may be more or less branched, often dichotomously, and 

 bear the reproductive organs at the top or on a level with the forks of the branches. 

 The EEPEODUCTIVE ORGANS {antheridia and sporangia) are borne on the same 

 individual, and then usually close together {monoecious) ; or on different individuals 

 {dioecious) . • i 



The ANTHERIDIA appear before the sporangia, and are situated immediately 

 below them {Chara), or above them {Nitella) ; their wall is composed of 8 flattened 

 triangular crenulate convex valves, the crenatures of which so interlock, that they 

 together form a sphere {globule). Each valve consists of 12-20 cells radiating from 

 a common centre, and each crenulation answers to an imperfect septum radiarting 

 from the centre of the valve. The inner surface of the valve is lined with a layer of 

 red granules ; the cavity of the globule is occupied by a colourless liquid, the thick- 

 ness of which gives the appearance of a whitish ring surrounding the antheridium. 

 At the centre of [the inner surface of] each valve is fixed perpendicularly an oblong 

 vesicle, which contains orange-coloured granules placed in a line, and presenting a 

 circulation observed by Thuret, and analogous to what occurs in the stems. The 8 

 vesicles emanating from the 8 valves converge towards the centre of the antheridium, 

 where their ends unite in a small cellular mass. A larger and flask-shaped ninth 

 vesicle attaches the antheridium to the plant, its enlarged base rising from a branch 

 of the Chara, while its opposite end penetrates the globule through a space between 

 the 4 lower valves, and reaches the central cellular mass. From this point emanate 

 a large number of flexuous hyaline chambered tubes, each joint of which contains 

 a filiform spirally- coiled antherozoid, furnished with 2 very long and fine setse, 

 which finally escapes from the joint in which it was imprisoned. 



The SPORANGIA are terminated by a corona, composed of 5 simple cells, whorled 

 and more or less persistent {Chara), or of 5 chambered cells simulating a corona, of 2 

 whorls, and very caducous {Nitella). The corona surrounds an orifice, which may 

 be regarded as a sort of micropyle. The walls of the sporangium are composed of 2 

 coats ; the outer membranous, colourless, transparent ; the inner formed of compressed 

 thick spiral tubes, containing colouring matters. The solitary spore is amylaceous, 

 and fills the sporangium; it is clothed with a membranous fawn-coloured coat, 

 marked, as weU as the outer membrane, with spiral striae due to the impression of 

 the tubes of the sporangium; it germinates without developing a protliallus. 



GENERA. 

 Chara. Nitella. 



