406 MR. B. CLARKE ON THE EMBRYOS OF ENDOGENS 



the cotyledon. On the face of the germinated cotyledon in Commelyna tuberosa, and 

 another species, tliere is always present a small process looking like a bud, which is not, 

 however, present on any of the succeeding leaves ; possibly it may be analogous to the 

 buds that occur on the ribs of the inferior palese of the Grasses, 



Juncacem. — As this family is intermediate between lAliacece and Cyperacem and their 

 allies, and its limits are not weU defined, its germination presented a more than usually 

 interesting subject of inquiry, and was rather expected to prove like that of the Liliacece. 

 Luzula campestris is, however, distinctly endorhizal, being more so than the Gyperacece, 

 and, I beUeve, strictly agrees mth the Commelyna cece in this character ; it may therefore 

 serve to show that Juncaceai have no near affinity with either lAliacece or Falmacece, 

 from which they further differ in the cotyledon, as growth advances, becoming elevated 

 on a cauliculus. The coleorhiza is of delicate texture, and disappears within a day or two 

 from the enlargement of the root *. The cotyledon has a well-defined opening for the 

 plumule, the first leaf of «hich is directly away from it. (Fig. 23.) 



Hydrochariilece. — Tliis family has the embryo (the plumule only being rather larger) 

 as well as the habit of Naiadece and their allies, and so may, perhaps, supply a connecting 

 link between the hypogynoiis and epigynous Endorhizse. It also agrees with them in 

 havmg the fii'st leaf of the plumule directly away from the cotyledon. 



JIarantacece. — The germination of Canna indica has been figured by Richard with 

 his usual accuracy t, with the exception of the primary radicle, which, from his figures, 

 might be supposed to possess a coleorhiza of the same kind as the secondary, which is not 

 at all the case. The coleorhiza of the primary radicle is of comparatively delicate texture, 

 and unless the germination is daily examined from its commencement, may escape 

 observation, as it very soon disappears entirely ; whereas the secondary radicles break 

 through the epidermis from a considerable depth, and the torn fissures through which 

 they escape remain for a much longer time. At the last stage figured, the coleorhiza of 

 the primary radicle has almost or entirely disappeared, so that the appearance of it there 

 represented is, I believe, only that of the lateral radicle on either side reflected do^m 

 upon it. The first leaf of the plumule alternates with the cotyledon, and as germination 

 advances, the cotyledon sends up a stipulary process, forming a short sheath for the 

 growing plumule. 



Alismacece and ButomacecB. — In the germination of Actinocarpus Damasonium the 

 plumule becomes elevated on a cauliculus, which elongates, while the radicle has scarcely 

 begun to protrude ; the first two leaves of the plumule are lateral, i. e. neither directly 

 towards the cotyledon nor directly away from it, but yet, as growth advances, the external 

 of the two shows a tendency to turn more directly away from it. Bntomus timbellaftis 

 germinates in the same way, the cotyledon having a very distinct fissure for the emission 

 of the plumule, but its first leaf is directly away from the cotyledon. The germination 

 was repeatedly observed, and no trace of a coleorhiza was perceptible. (Kgs. 24 & 25.) 



* The coleorhiza cannot be seen unless the seed is first completely deprived of its mucilaginous coat by placing it in 

 water for two or three days, when it swells, and is easily removed. If this is not done, the radicle becomes covered 

 with mucus, so as entirely to prevent observation. 



t Ann. du Museum d'Hist. Nat. tom. xvii. pi. :>. figs. 3, 4, 5, 6. 



