192 SIPHONACE^K. 



Besides the colouring matter or endochrome dispersed 

 through the plant, and which forms in part the fructification, 

 many plants of this order are furnished with little bodies 

 called coniocystte, through which the species is reproduced. 

 These bodies are formed at the sides of the cells, and at first 

 manifest themselves as small mamillae, or tubercular or club- 

 shaped ramuli, containing a denser colouring matter than 

 other parts of the frond. A diaphragm is formed at their 

 base, and thus a cell is enclosed, in which the colouring 

 matter becomes further organized and gradually compacted 

 into a sporangium. In some Vaucherics (as in V. clavata] 

 a portion of endochrome at the apex of a branch swells, be- 

 comes dense, and at length consolidated and separated from 

 that beneath it by a diaphragm. Thus a propagulum or 

 gemmule is formed, which, at maturity, separates from the 

 frond, and becomes a reproductive body. It is clothed with 

 vibratile cilia, by which it moves about until it has fixed it- 

 self, and then, lengthening at each end, it changes into a 

 filament, which gradually assumes the character proper to 

 the species, and becomes a new individual. Coniocysta 

 may commonly be found on Vaucheria in spring, and on 

 the filaments of Codium lament osum in summer, but have, 

 hitherto, been only noticed in one species of Bryopsis. 



The plants of this order are widely dispersed. All our ge- 

 nera are cosmopolitan, and Codium tomentosum is as com- 

 mon on the shores of the Pacific, from high northern to high 

 southern latitudes, as it is in the Atlantic and Mediterranean. 

 A large number of genera are peculiar to warmer parts of the 

 sea, some of them among the most elegant of all marine 

 plants. Among these are Acetabularia, a Mediterranean and 

 West Indian genus, with thread-like stems crowned with a 

 papery cup (composed of filaments united together) fringed 

 with byssoid ramuli like those of a Bryopsis ; and Anadyo- 

 mene, a native of the same seas, having expanded fronds like 

 those of an Ulva, composed of tubular cells arranged in 

 starry patterns. If Caulerpa belong, as I have always 

 thought an opinion not shared by all my fellow-students, 

 and therefore to be reconsidered to this order, a very re- 

 markable tropical and subtropical genus should be mention- 

 ed, which carries the type of structure peculiar to these 

 plants to its highest pitch. That genus contains numerous 

 species, distinguished among Algae as rising from prostrate, 

 rooting stems, that form a compact mat, and serve to bind 

 together the loose sands on which they grow. They are 



