420 



MORPHOLOGY. 



containing the small quantity of albumen which exists in its cavity, as 

 in Orontium aquaticum (fig. 262.). The radicle is sometimes simply 

 roundly apiculate, sometimes elongate-cylindrical, and then suddenly 

 truncated into a surface occasionally umbilicate in the centre, e. g., 

 Potamogeton (fig. 255.), &c.; sometimes very thick, flat below and at- 

 tenuated above, as it passes into the cotyledon so that the embryo repre- 

 sents an erect cone (in many Palm?, fig. 261.). All these anomalies are 



262 



f c 



easily traced to the fundamental type through the progressive deve- 

 lopment. 



In most of the cases hitherto named, the position of the terminal bud 

 on the ripe embryo is not at all unnatural. Originally occupying the 

 apex of the embryo, it often appears lateral on account of the great 

 mass of the cotyledon, forming an angle with the axis of the latter ; 

 sometimes, however, the cotyledon is so strongly developed that it forms 

 a right angle with its axis (fig. 257.), consequently also with the axis of 

 the radicle, which usually appears as a direct prolongation of the coty- 

 ledon. The structure in Lemnacece is apparently the most aberrant 

 (fig. 263.) ; here the ripe embryo is a large, longish, conical, or ovate 

 mass ; below, at the thicker end, which is turned toward the micropyle, 

 therefore on that account already to be determined as the radical end, a 

 very small transverse slit is exhibited. If a cross section is made 

 through the embryo here, we see that behind this slit the bud, consisting 

 of a flattish rudiment of the stem, lies in such a direction that its axis is 

 almost parallel with that of the cotyledon, and its apex also directed 

 toward the micropyle (fig. 263, C. c.) ; on the other side of the radical 



263 



61 Chamadorea schiedeana. Embryo in longitudinal section, a, Radicle ; b, cotyledon ; 

 c, slit with the plumule. 



68 Orontium aquaticum. A, Embryo : a, radicle ; b, cup-shaped cotyledon ; c, free 

 plumule. J9, The same seen from beneath : c, the point of attachment of the funiculus 

 (hilum). C, Longitudinal section of the same : a, b, c, as in A ; x, the cavity of the 

 cup-shaped cotyledon. 



863 Lemna gibba. A, Very young embryo : , radicle with the torn suspensor ; b, co- 



