14 



CONFERVACE^. 



[Algals. 



Order II. CONFERVACEiE.— Confervas. 



Confervacefe, Endl. pen. Suppl. III., p. 10. Zoospermeae, J. Agh. Alg. Med. 1. Synsporese 

 and Zoospermese, Decaisne in Ann. Sc. N. 2 ser. 18. 305. 



Diagnosis. — Vesicular, filamentary or membranous bodies, multiplied by zoospores 

 generated in the interior, at the expense of their green matter. 



Water plants, not commonly of a gi'een colour, but occasionally olive, violet, and red ; 

 inhabiting the ocean in some instances, but more commonly found in fresh water ; some 

 of them even belonging to both kinds of fluids; some foimd in 

 ^ mud, others floating freely, most attached, in some way, on rocks 



or as parasites. Cells "^sohtary or many, globose, elliptical, 

 cylindrical, or tubular ; sometimes variously branched ; some- 

 times formed in shmy matter in which they are scattered, or 

 irregularly heaped, or placed one above the other in a regular 

 series forming an articulated frond ; some disposed in several 

 rows and forming a thin layer, or some combined in the form 

 of a net. Their mode of growth by a subdivision of the cells, 

 of ramification by a lateral extension of such cells, a dividing 

 partition being eventually formed. The p>ropagation by sporidia 

 (internal cells, or a gelatinous substance which organizes itself 

 into cells,) found in each cell, singly, or in a definite, or indefi- 

 nite number, formed from the colourmg matter of one or more 

 cells, or sometimes by the copulation of distinct mdividuals, and 

 discharged bv the opening or absorption of the mother cell. — 

 Endl. 



If doubts exist as to the Vegetable nature of the last order, 

 or of some part of it, no question arises as to what that of 

 Confervas is. Its genera are now admitted on all hands to 

 be plants, since M. Decaisne's important discovery of the vege- 

 table nature of several things which had been pre^^ously 

 regarded as Zoophytes. Nevertheless, it is curious to see how 

 much, at one period at least of their existence, they have of an 

 animal nature, if the power of moA^ng from place to place is to 

 be taken as an indication of such a quality. It seems incon- 

 testable, notwithstanding the denial of Mohl and others, that 

 many of the Conferva tribe, especially of the genera Conferva, 

 Ulva, and their near allies, produce in their tubular threads 

 reproductive bodies, or spores, which after a time acquire a 

 power of rapid, and quasi- voluntary motion while in the inside 

 of their mother ; that by degrees, and in consequence of their 

 constantly tapping against the soft side of the cell that holds 

 them, they escape into the water ; that when there they swim 

 about actively, just Uke animalcules ; and at last retreating to a shady place, attach 

 themselves to a stone or some other body, lose their locomotive quaUty, and thence- 

 forward genumate and grow hke plants.— (/. Ag. Ann. Sc. Nat. 2 ser. vol. 6.)* It is 



* " The filaments of Conferva arrea," says^the younger A gardh, "are, as is well known, articulated or 

 divided at equal distances into little compartments (joints), which have no communication among them- 

 selves other than what results from the permeability of the dissepiments. The green matter contained 

 m these jomts appears at first altogether homogeneous, as if it were fluid ; but in a more advanced state 

 It becomes more and more granular. The granules are, at their formation, found adhering to the inner 

 surface of the membrane, but they soon detach themselves, and the in-egular figure which they present at 

 first passes to that of a sphere. These granules congregate by degrees in the middle of the joint, into a 

 mass, at first elliptical, but which at length becomes perfectly spherical. AU these changes are conform- 

 able to phenomena known in vegetable life ; those which are to follow have more analogj' with the pheno- 

 mena of animal life. At this stage an important metamorphosis exhibits itself, bv a motion of swarming 

 (un mouvement de fourmillement) in the green matter. The granules of which it is composed detach 

 themselves from the mass, one after another, and having thus become free, they move about in the vacant 

 space of the joint with an extreme rapidity. At the same time, the exterior membrane of the joint is 

 obserA-ed to swell in one point, till it there forms a little mammilla, which is to become the point from which 

 the moving granules finally issue. By the extension of the membrane for the formation of the mammilla, 

 the tender fibres of which it is composed separating, cause an opening at the end of the mammilla, and it 



K ^J^^^^~}- Protococcus viridis ; 2. the same beginning to develop ; 3. the same more advanced ; 4 & 

 5. Schizogonmm murale : 6. A fragment of Ulva (Prasiola) furfuiacea (Ktitzing). 



Fig. III. 



