r. Q & LYC0P0D1 ACE^E. [Acrogexs. 



this structure is the pro-embryo. The cells are at first in a single layer hut .the 

 central ones soon become divided by horizontal septa, so as to produce a double 

 I, v, r, and finally, four or more tiers of cells one above another. The outline of the 

 pro embryo, seen from above, is cellular, spreading over the upper part of the spore. 

 On its surface appear the so-called ovules. The first is produced at the apex of the 

 pp embryo ; the rest, to the number of twenty or thirty, arranged upon its surface in 

 il, ,e lines corresponding to the slits by which the outer coat of the spore bursts 

 These ovules, closely resembling those of Salvinia, Pilulana, the Ferns &c, consist of 

 :t riobular cell, surmounted by four cells, which rise up into four papilla? and leave a 

 canal, or intercellular passage between them, leading down to the globular cell or 

 .mln-sac. The four cells are usually developed into four or five cells, one above 

 the other, by the production of horizontal septa; sometimes they are developed 

 unequally and to a considerable extent, so as to form papilla?, presenting an ormce 

 between them at some point on the outer surface, indicating the canal leading down 

 to the embryo-sac. . . . 



During the development of the ovules, a delicate parenchyma is produced in the 

 great cavity of the spore, finally entirely filling up this spore. Before it has com- 

 pletely filled it, the embryo makes its appearance in the embryo-sac ot one ot 



the ovules. . , .i • n 



The first change in this sac is the appearance of a nucleus ; from this cells are 

 developed representing the suspensor of the embryo. The cells of the suspensor 

 multiply and form the process which penetrates down into the parenchyma of the 

 cavity of the spore ; at the lower end may be detected the embryo, a minutely 

 cellular body. Dr. Mettenius never saw the embryo produced in the embryo-sac 

 before the suspensor had broken through the bottom of it to penetrate the parenchyma 

 of the spore-cell ; it was always within this parenchyma, and attached to the end of 

 the suspensor. In this point he is decidedly opposed to Hofmeister, who states that 

 the embryo originates in the embryo-sac, whence a young embryo attached to its 

 suspensor may easily be extracted from the spore. 



The part of the embryo opposite to the point of attachment of the suspensor 

 corresponds to the first axis of the Rhizocarpea?, which never breaks out from the 

 spore-cell in Selaginella ; it pushes back the loose parenchyma of the spore-cell as it 

 becomes developed, and when completely formed, is surrounded by a thin coat 

 composed of several layers of the parenchymatous cells much compressed, enclosed 

 in the still existing inner coat of the spore. On one side of the point of attachment 

 of the suspensor the embryo grows out towards the point where the spore-cell has 

 been ruptured, thus apparently in a direction completely opposite to the end of the 

 axis. As it enlarges, it produces in this situation the leafy stem growing upwards, 

 and the adventitious root turning downwards. The pro-embryo is at first distended 

 like a sac, and finally broken through on the one side by the first leaf, on the other 

 by the adventitious root ; upon it may be observed the numerous abortive ovules, 

 with their embryo-sacs filled with yellow contents; part of its cells grow out into 

 radical hairs. I h: Mettenius several times saw two young plants produced from one 

 spore; the ends of their axes lay close together, and separated inside the cavity of 

 the spore. No account is here given of the characters exhibited by the small spores, 

 or of anything like a process of fertilization ; yet there is indicated in the foregoing 

 description of the so-called ovules, a clear analogy between these bodies and the 

 so-called ovules of the Ferns and Rhizocarpese. These points will be referred to again 

 at the close of the report. Hofmeister further states that spiral filaments are produced 

 from the small spores of Selaginella, but he does not say that he has seen them, or 

 give any authority. So far Henfrey. 



Mr. Thuret reports (Recherches sur les Zoospores des A Igues, &c. p. 81) that he has 

 often tried to make the spores of L. clavatum and inundatum grow, but could never 

 succeed, any more than with those of Adder's-tongues (Ophioglossacese), which are 

 very analogous to those of Lycopods. "Must we then conclude," he says, "with 

 U . Spring, that these genera consist exclusively of males 1 I would prefer to suppose 

 that the true fructification of these plants still remains to be discovered." 



(See also page 53 d.) 



