46 ON SEEDLINGS 



growing in length, and in consequence send out two long 

 wings, so that they are divided almost to the base (fig. 89, A). 



In Shorea, again, the division of the cotyledons is perhaps 

 due to an internal process of the seed. I have not, how- 

 ever, had an opportunity of examining a specimen. 



In Eucalyptus (fig. 38) we have a different case. The 



FIG. 89. Ipomcea dasysperma. A, embryo, x 2. B, section of seed after removal 

 of dorsal surface, embryo, and endosperm, x 2. C, side view of ditto, x 2. 



embryo is (with the exception of the petioles) straight or 

 nearly so, fleshy, white, occupying the whole of the seed, and 

 conforming to it in general outline ; the cotyledons are 

 deflexed and convolute round the radicle, which the lobes 

 equal in length, while half of one cotyledon lies over half the 

 other ; one half of each consequently lying against the testa. 

 The radicle is stout, fleshy, truncate 



testa, but otherwise entirely enclosed 

 by the folded cotyledons. The true 

 length of the cotyledon is determined 

 by the distance between the end of 

 S ^ petiole and the opposite pole of 

 cutaway : jp, petiole ;p', cut end the seed. The side of the cotyledons, 



of petiole ; ^.l, inner lobe of .,-,,, i ,,, 



cotyledon, x 4. however, being folded back, that part 



which lies beyond the petioles is 



enabled by folding round the radicle to widen, and this conse- 

 quently gives the cotyledons their more or less pronounced 

 hour-glass shape. 



Moreover, in speaking of emarginate cotyledons, we must 

 distinguish between two very opposite cases, of which I may 

 take Galium Aparine and (Enothera Lindleyana as illustra- 



