OF THORNS. 265 



tender and fugacious nature, are sometimes terminated 

 by spiny points, as in Cuviera. 



The persistent or sterile stamens of someByttneriaceae 

 acquire so firm a texture, that they may take the name 

 of spines. 



The styles often remain after flowering, and form at 

 the apex of the fruit spines often very hard and long: 

 as in Martynia. 



Thus all the organs of plants, except the roots and 

 seeds, are capable of hardening or being prolonged into 

 spines ; so that it is impossible to say that a spine is an 

 organ properly so called, but that it ought to be con- 

 sidered a particular state of vegetation. 



All thorns which do not result either from the in- 

 duration or prolongation of any of the organs which I 

 have mentioned, bear the name of Prickles, and may 

 be considered as kinds of hairs larger, stronger, and 

 harder than usual. There are cases where the transition 

 from hairs to spines is so gradual as to show their iden- 

 tity of nature : thus, in the bundles of hairs which spring 

 from the axils of the leaves of Opuntia, we see some 

 larger than the others, and transformed into very long 

 and hard prickles. It is nearly the same in Roses : we 

 often see the glandular hairs of their peduncles and 

 calyces harden into true prickles. There are cases, 

 then, where there can be no doubt that prickles are 

 analogous to hairs. I know that it cannot be affirmed 

 in a general manner, except by means of analogy. 



Prickles are distinguished from spines in their never 

 taking the place of any of the great organs of the plant ; 

 they are usually found upon the stems, branches, pe- 

 duncles, and petioles, and upon the nerves of the leaves, 

 calyx, or even of the petals ; but they never terminate 

 either the fibres or nerves ; whilst spines, being indura- 

 tions of organs, are always placed at their ends. This 



