EMERGENCIES 187 



Thus examine branches of Rose, or TODDALIA 

 ACULEATA, or LANTANA, or RUBUS. There are curved 

 prickles on the branches and leaf stalks, but unlike 

 those that we have studied, they seem to be in 

 no particular arrangement, and are scattered without 

 reference to the position of any other organ. We 

 cannot therefore consider them as modified branches, 

 stipules or anything else, but only as emergencies, 

 that is, merely raised and hardened portions of the 

 outer tissues. It is quite easy to remove one with a 

 small piece of the cortex, for they have no connexion 

 with the central part of the shoot, as have thorns 

 that are modified branches. 



The same is the case with the strong hard thorns 

 that occur on the branches and stem of ERYTHRINA 

 INDICA, and of BOMBAX MALABARICUM, the Silk-cotton 

 tree. 



They of course, serve the same function as other 

 thorns from the physiological point of view they 

 have the same value, in homology they are utterly 

 different, being, like hairs, outgrowths of the surface. 



