150 INTRODUCTION TO CRYPTOGAMIC BOTANY. 



species occur in the Antarctic Flora. Their size is in general 

 so small as to make it improbable that they can be of any 

 practical utility. 



9. Conjugate, Berk. 



Threads articulate ; their endochrome generally assuming 

 some definite arrangement, often forming one or more spirals. 

 Spores or zoospores formed by the union of two endochromes 

 in the same or contiguous threads, or from the division of a 

 single primary endochrome. 



123. Perhaps among all the Chlorosperms there are none 

 more worthy of attention, whether as regards their com- 

 ponent cells, or their mode of fructification. The first ex- 

 hibit many phenomena illustrative of cellular formation in 

 general, and its transformation into spiral vessels, while the 

 latter opens a wide field for investigation in the variety 

 of phases it assumes. The threads of these plants in their 

 primary condition consist of a row of cells, very much as in 

 ordinary Confervce. The endochrome, however, shows more 

 evident traces of organization, even in the simpler cases 

 exhibiting at least larger gramiles disposed in rows ; but in 

 others, one or more broad spiral bands, with larger granules 

 at different portions of their course, or binary masses often 

 assuming a stellate form. In some cases a large cytoblast is 

 distinctly visible, from whence proceed delicate rays, exactly 

 like those from the nascent spores of Anthoceros.* These 

 cytoblasts have sometimes a second nucleus ; sometimes they 

 are positively central, sometimes attached to the walls, and their 

 function is as obscure as in higher plants. In many instances, 

 the inner membrane of each cell is sLagularly depressed at 

 either end by a sort of introsusception, and sometimes it pro- 

 trudes into the neighbouring cell (Fig. 38, b.) ; and where this 

 is the case the main thread is often disarticulated, and the 

 liberated joint forms the ground-work of a new thread, as in 

 the Oscillatorice. The external coat, which in this instance 

 gives way so easily, varies greatly in consistency in different 

 species. Sometimes it is simply membranous ; sometimes it 

 is gelatinous, and occasionally very thick, varying in different 

 * Mohl. in Linn., vol. xiii. tab. v. 



