CHAP. II. EMBRYO. 215 



embryo as to be undistinguisbable, but is indicated externally 

 by a little slit above the base (Plate VI. fig. 6. B. e), within 

 which it lies until called into development by germination. 



The exceptions to what has been now described ought, 

 like those of dicotyledons, rather to be called remarkable 

 modifications. Much stress has been laid upon them by se- 

 veral writers, who have thought it requisite to give particular 

 names to their parts. To me, however, it appears far more 

 advisable to explain their analogies without the unnecessary 

 creation of new and bad names. In Graminecs (Plate VI. 

 fig. 4.) the embryo consists of a lenticular body lying on the 

 outside of the base of the albumen on one side, and covered 

 on its inner face by that body, and on its outer face by the 

 testa : if viewed on the face next the testa, a slit will be 

 observed of the same nature as that in the side of the 

 embryo of Aroideae ; opening this cleft a small conical pro- 

 jection is discovered, pointing towards the apex of the seed. 

 If the embryo be then divided vertically through the conical 

 projection, it will be seen that the latter (c) is a sheath includ- 

 ing other little scales resembling the rudiments of leaves ; that 

 that part of the embryo which lies next the albumen {d), and 

 above the conical body, is solid ; and that the lower extremity 

 of the embryo [e) contains within it the indication of an in- 

 ternal radicle, as in other monocotyledons. In this embrj^o 

 it is to be understood that the conical projection is the plu- 

 mule ; that part of the embryo lying between it and the 

 albumen, a single scutelliform cotyledon ; and the lower point 

 of the embryo, the radicle. In wheat there is a second small 

 cotyledoii on the outside of the embryo, inserted a little lower 

 down than the scutelliform cotyledon. This last is called 

 scutellum by Gaertner, who considered it of the nature of 

 vitellus. Richard considered the scutelliform cotyledon a par- 

 ticular modification of the radicle, which he called hypohlastus; 

 the plumule a form of cotyledon, called blastus ; the anterior 

 occasional cotyledon a peculiar appendage, named epihlastus ; 

 and the radicle a protuberance of the caulicule, called radicu- 

 loda. He, further, in reference to this peculiar opinion, 

 termed embryos of this description macropodous. In these 



p 4 



