THE DISPKR8ION OK SKKDS AND SI'OKES. 113 



others. Thus rabbits eat the leaves, and thrushes 

 the berries, of the deadly nightshade without injury, 

 and strychnine appears to have no injurious effects 

 upon monkeys. It seems probable, therefore, that 

 these poisons are produced, not for the purpose of 

 destroying the agents concerned in dispersion (though 

 they may be so in a few instances), but rather to 

 keep away undesirable visitors. When a poisonous 

 principle first began to be developed in any particular 

 fruit, the birds which fed on it, we should naturally 

 suppose, would become gradually inured to the 

 poison until it had completely lost its effect. The 

 liking of parrots for pepper-corns is in all probabilitj' 

 an acquired taste. Immunity from particular poisons 

 might be acquired in the same way that the strong 

 mandibles have been developed in relation to hard- 

 shelled fruits. Where poisoning occurs it would 

 seem to be accidental, and should be regarded as 

 arising from imperfect instincts, or as the inevitable 

 concomitant of a transition stage in development 

 towards more perfect adaptation. On the same 

 principle we should be disposed to explain the case 

 of those aroids which, according to Delpino, poison 

 the snails on which they depend for fertilisation. 



There are a few cases in which fruits, although 

 not succulent, appear to depend on birds for the 

 dispersion of their seeds. Ophiocai'yon paradoxum, 

 the snake-nut of Demerara, is so called on account 

 of its peculiar coiled embryo presenting a striking 

 resemblance to a small snake. The likeness is so 

 marked that when the egg-like capsule is opened 

 one involuntarily starts back from the supposed 

 reptile. It would seem that the imitation here is 

 intended as a deception, for if a bird seizes the seed 

 under the impression that it has got a snake, and 

 after carrying it some distance discovers its mistake 

 and drops the seed, then the object of the plant — 

 dissemination — ^will be attained, and that without any 

 outlay in the shape of succulent pulp or saccharine 

 matter. 



