LECT. XI.] CAULINAR AND FOLIAR APPENDAGES. 651 



common cutis of the part on which they are si- 

 tuated is reflected. Willdenow states the prickle 

 to be vascular ; but I have not been able to detect 

 any vessels in it, unless we regard the tubular 

 cells as vessels *. They are a more permanent ap- 

 pendage than thorns ; not at all liable to disap- 

 pear by culture ; and, consequently, are better 

 fitted for forming specific distinctions. 



Linnaeus regarded thorns, prickles, and bristles 

 as the armour of plants ; and the poetical ima- 

 gination of Darwin has led him to suppose, that 

 the great Author of all things has impressed on 

 organized bodies " a power of producing armour 

 " to prevent those more violent injuries which 

 "would otherwise destroy them -f- ;" and, conse- 

 quently, that plants, now unprotected, may ob- 

 tain bristles and other defensive organs in the pro- 

 gression of time. But although the depredations 

 of animals upon the tender foliage of plants are 

 occasionally checked by these organs, yet, such 

 fanciful notions as those I have just quoted, and 

 indeed most of those which our reasonings upon 

 final causes lead to, are neither philosophical nor 

 accordant with correct observation; and we must 



* Willdenow, in his Principles of Botany, 270, says, 

 " This (the prickle) consists of reticular, more or less ex- 

 " panded, adducent vessels, and a few air vessels, and is co- 

 " vered with the vascular cutis. 1 ' Translation. 



f Phytologia, Sect. xiv. 3. 2. 



