SECT. 1 



CRYPTOGAMS 



423 



construction is only found among other Thallopliyta in certain Brown Algae {e.g. 

 Spcrmatochnus). 



Each cell contains one normal nuclens derived from a karyokinetic 

 division. As a result of the fragmentation of its original luicleus, 

 however, each internodal cell is provided with 

 a number of nuclei which lie embedded in an 

 inner and actively moving layer of parietal 

 protoplasm. Numerous round chloroplasts are 

 found in the internodal cells. 



Asexual reproduction by means of swarm- 

 spores or other spores is unrepresented in the 

 Characeae. Sexual reproduction, on the other 

 hand, is provided for by the production of egg- 

 cells and spermatozoids. The female organs are 

 ovate. They are visil)le to the naked eye, and, 

 like the spherical red-coloured antheridia, are 

 inserted on the nodes of the lateral axes. With 

 the exception of a few dioecious species, the 

 Characeae are monoecious. The fertilised egg- 

 cell develops into an oospore in the germina- 

 tion of which, as we are forced to assume, 

 the reduction-division of the diploid fusion- 

 nucleus takes place. The Characeae thus exhibit 

 no alteration of haploid and diploid generations 

 but a succession of haploid gametophytes. 



The male organs (Fig. 364, a) are developed 

 from a mother-cell that first becomes divided 

 into eight cells. Each octant by two tan- 

 gential walls gives rise to three cells. In this 

 way are derived the eight external tabular 

 cells of the wall, the cavities of which are in- 

 completely partitioned by septa extending in 

 from the cell wall ; the eight middle cells form 

 the manubria and become elongated ; the eight 

 innermost cells assume a spherical form as the primary head-cells. 

 Owing to the rapid surface growth of the eight shield cells a cavity 

 is formed within the male organ into which the manubria bearing the 

 head-cells project. The latter form 3-6 secondary head-cells and from 

 each of these arise 3-5 long unbranched spermatogenous filaments. 

 These are composed of disc-shaped cells from each of which a spirally 

 wound spermatozoid with tAVO cilia is liberated (Fig. 99, A). The 

 spermatogenous filaments or antheridia may be compared morpho- 

 logically to the plurilocular gametangia of the Brown Algae. These, 

 as in Stilophora for instance, may consist of simple rows of cells and 

 be grouped together in sori. The male organ of the Characeae, which 



Fki. 363.—C7iarafiwiUis. End 

 of main shoot. (Nat. size.) 



as a whole is commonly spoken of as an antheridium, thus contains 



