96 RUDIMENTARY COTYLEDONS. CUAP. II. 



specimen was only -r^-th and in another ^th inch in 

 length; it ultimately appeared as if seated halfway 

 down the hypocotyl. In both these species the hypo- 

 cotyl is so much enlarged, especially at a very early 

 age, that it might almost be called a corm. The lower 

 end forms a heel or projection, the use of which will 

 hereafter be described. 



In Cyclamen Persicum the hypocotyl, even whilst still 

 within the seed, is enlarged into a regular corm,* and 

 only a single cotyledon is at first developed (see former 

 Fig. 57.) With Ranunculus ficaria two cotyledons are 

 never produced, and here one of the secondary radicles 

 is developed at an early age into a so-called bulb.f 

 Again, certain species of Chserophylluni and Corydalis 

 produce only a single cotyledon ;{ in the former the 

 hypocotyl, and in the latter the radicle is enlarged, 

 according to Irmisch, into a bulb. 



In the several foregoing cases one of the cotyledons 

 is delayed in its development, or reduced in size, or 

 rendered rudimentary, or quite aborted ; but in other 

 cases both cotyledons are represented by mere rudi- 

 ments. With Opuntia lasilaris this is not the case, 

 for both cotyledons are thick and large, and the 

 hypocotyl shows at first no signs of enlargement ; but 

 afterwards, when the cotyledons have withered and dis- 

 articulated themselves, it becomes thickened, and from 

 its tapering form, together with its smooth, tough, 

 brown skin, appears, when ultimately drawn down to 

 some depth into the soil, like a root. On the other 



* Dr. H. Gressner, ' Bot. Zei- Vauclier's account (' Hist. Phys. 



tung,' 1874, p. 824. des Plantes d'Europe,' torn. i. 1841, 



t Irmisch, * Beitrage zur Mor- p. 149) of the germination of the 



phologie der Pflanzen,' 1854, pp. seeds of several species of Corv- 



11, 12; 'Bot. Zeitung,' 1874, p. dalis, that the bulb or tubercule 



805. begins to be formed at an ex- 



J Delpino, * Rivista Botanica,' tremely early age. 

 1877, p. 21. It is evident from 



