I 



458 CONSERVATIVE ORGANS. [LECT. IX. 



duces a living progeny without sexual intercourse ; 

 and " this offspring produces others by this solitary 

 "propagation, till the tenth generation; then a 

 " sexual progeny of males and females is produced," 

 and eggs are laid from their copulation*. Now, 

 although no experiments have been made to ascer- 

 tain how long a bulbiferous plant may be propa- 

 gated by bulbs only, checking every effort for the 

 production of seed, yet, we know that in bul- 

 biferous plants, when the production of bulbs is 

 considerable, the seeds are seldom ripened, and 

 even the sexual organs are often defective; and the 

 reverse happens when the production of bulbs is 

 either scanty or defective. The analogy between 

 the successive lateral generations of the aphis, 

 before males and females are formed to recom- 

 mence the propagation by eggs, and the pro- 

 gressive formation of bulbs before a flower-bulb is 

 the result, is still more striking. The bulb, which 

 is raised from the seed, produces one or two leaves 

 only, and bulbs one degree more perfect than it- 

 self; which in their turn yield stronger plants and 

 more perfect bulbs; and in this manner a suc- 

 cession of leaf-bulbs are annually evolved for four 

 or five years, till at length a flower-bulb and a 

 seminal progeny are produced. The vegetable, 

 however, differs from the animal in producing, 

 at the same time with the flower-bulb, other 



* Amcenit. Academ. vol. vii. Darwin's Phytologia, ix, 3, 1. 



