4 



384 



SIR J. LTJBBOCK — PnXTOBTOLOGlCAL OBSEUVATIOXS. 



Moreover, in speaking of einarginate cotjledoiis, we must dis- 

 tinguish between two very opposite eases, of whicli I may take 

 Galium Aparine and ^nothera Lindleyana as illustrations. In 

 the former the cotvledons commence witli an entire end (fig. 113), 

 and subsequently, not as a rule till they have left the seed, become 



Fig. 113. 



Fig. 111. 



Fig. 113. Young seedling of Galium Apartne, x2. 

 Fig. 114. Ditto, a few days old^rf X2. 



fiiZ. 11-1); in (Enothern TJndlei/nna. on th 



J 



the cotyledons are at first emarginate, but gradually cease to 

 be so. The embryo gradually appropriates all tbe perisperm, 

 but the supply being largest at the wider end of the seed, this is 

 the last part to be absorbed- In neither of these cases does the 

 eniargination appear to be directly due to the structure of tbe 

 seed, nor to be in itself of any advantage to the plant. It seems 

 rather to depend on the conditions of growth. In G. Aparine 

 the cotyledon terminates in a peculiar gland*, wdiich would 



* This gland has already been mentioned by Gravis in his work on TJrtica 

 dloica, p. 139. He observes that about a d'>zen small stomata occur on it, 

 while they are entirely ab:;ent on the rest of the upper surface. He regards 

 it as a watcr-glanci, ** un organ destin^ a remedier 4 I'exces de tension dantf 



m 



I'appareil aquifere." 



