I)KTAII.S OF A VAM'AHLK PRICKLY PKAK 



Old and youiij^ joints, fUnwrs and hiid of Opuutid suburmutu, ;in cntin.- ])lanl of wliich was 

 shown in Fi^. 17. 'I'his jjlanl is a pirfi'ttly spinrkss one-, with frw s])icul(.'s, and was 

 sclccU-d from a mass of spiny plants of the same kind in tlic Devil's River rcj^ion of Texas. 

 It is now beinj^ propaj(ated l)y euUinj^s, so that it is not likely to revert to the aneestral, 

 spiny eondition of the speeies. The old joint, at the bottom, shows the spinele.ss condi- 

 tion; the youn^ joint, above, shows the rudimentary leaves, which drop off in a few weeks. 

 It will be remembered that the prickly jjcar i)lant ecjnsisls merely of stems, which are 

 flattened out; the leaves were lonjj ajjo reduced, in the process of evolution, to slijjht 

 fleshy protuberances such as here shown, which are soon lost. (Fig. 18.) 



