180 CONSERVATIVE ORGANS. [LECT. IV. 



the roots are protruded. The number of the 

 layers varies : the exterior are thin and semipellu- 

 cid, being 1 formed simply of two membranous cu- 

 ticles, with equi-distant bundles of vessels running 

 longitudinally through them : the interior are 

 more fleshy, the cells being filled with nutritious 

 juices. A transverse section of the bulb exhibits 

 the continuous character of each layer *. The 

 new flower bulb is formed nearly in the centre of 

 the old bulb, at the base of the stem ; but in 

 general, there are several leaf bulbs formed : one 

 or more within the second or the third layer from 

 the surface, and others laterally and altogether 

 exterior to the old bulb. The outer layers only of 

 the old bulb are completely exhausted in one sea- 

 son ; hence the bulb in several subsequent seasons 

 appears to be the same which originally flowered, 

 only much enlarged. The lateral bulbs separate, , 

 and, as in similar cases, maintain an independent 

 existence. In the Tulip, the bulb consists usually 

 of four concentric layers only (independent of the 

 common coat), the outermost of which may be 

 termed fleshy ; but being nearly diaphanous, the 

 longitudinal vessels are seen running through it 

 at equal distances, with the intervening spaces on 



* Vide Plate 3. fig. 1. which represents the transverse section 

 of the bulb of Narcissus Jonquitta : a. a. two young bulbs 

 rising betwixt the second and third layers ; b. the roots pro- 

 truded from the radical plate, which is hid by the position of the 

 bulb. 4 



