LECT. IX.] LEAVES. 507 



prominent on the back or under surface of the 

 leaf, and have been very improperly denominated 

 nerves and veins-, for nothing has yet been dis- 

 covered in vegetables bearing any analogy to 

 nerves ; and as the fasciculi ' contain both con- 

 ducting and returning vessels, they may be 

 termed arteries with as much propriety as veins. 

 But the terms, notwithstanding their absurdity, 

 being in general use, require to be explained. 

 The larger fasciculi are denominated nervi and 

 costas, and the smaller vence, in whatever man- 

 ner they are disposed throughout the leaf; but 

 the terms nervosum, costatum, and venomm, imply 

 distinct dispositions of the fasciculi. 



A leaf is said to be nerved (nervosum) when 

 the larger fasciculi run, in simple, slightly curved 

 lines, from the base to the apex ; and the leaf is 

 named according to their number, among which 

 the midrib is reckoned as one. Thus three-nerved 

 (trinervis), 6i, (page 509), means that the leaf has 

 one longitudinal fasciculus of vessels on each side 

 of the midrib, taking its origin from the base ; and 

 five-nerved (quinquenervu), that it has two lon- 

 gitudinal fasciculi on each side of the midrib, un- 

 der the same circumstances. It is seven-nerved 

 (septemnervis), 62, when there are three fasciculi 

 on each side; nine-nerved (novemnervis), when 

 there are four ; and many-nerved (multinervis}, 

 when the number on each side exceeds four. The 



