STRUCTURE.] OTHER ANOMALIES. C>7 



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

 including 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 indi- 

 cation of an internal radical, as in other monocotyledons. In 

 this embryo it is to be understood that the conical projection 

 is the plumule ; 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 cotyledon on the outside of the embryo, inserted a little 

 lower down than the scutelliform cotyledon. This last is called 

 scutellum by Gartner, who thought it of the nature of vitellus. 

 Richard considered the scutelliform cotyledon a particular 

 modification of the radicle, and called it hypoblastus ; the plu- 

 mule a form of cotyledon, or blastus ; the anterior occasional 

 cotyledon a peculiar appendage, or epiblastus ; and the radicle 

 a protuberance of the caulicule, or radiculoda. He further^ 

 in reference to this opinion, termed embryos of this descrip- 

 tion macropodal. In these ideas, however, Richard was wrong, 

 as is now well known. 



From what has been stated, it is apparent that dicotyledons 

 are not absolutely characterised by having two cotyledons, 

 nor monocotyledons by having only one. The real distinction 

 between them consists in their endorhizal or exorhizal ger- 

 mination, and in the cotyledons of dicotyledons being opposite 

 or verticillate, while they are in monocotyledons solitary or 

 alternate. Some botanists have, therefore, recommended the 

 substitution of other terms in lieu of those in common use. 

 Cassini suggests isodynamous or isobrious for dicotyledons, 

 because their force of development is equal on both sides ; 

 and anisodynamous or anisobrious for monocotyledons, because 

 their force of development is greater on one side than on the 

 other. Another writer, Lestiboudois, would call dicotyledons 

 exoptiles, because their plumula is naked; and monocotyle- 

 dons endoptiles, because their plumule is inclosed within the 

 cotyledon; but there seems little use in these proposed 

 changes, which are, moreover, as open to objections as the 

 terms in common use. 



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