''DEFENCE, NOT DEFIANCE.'' 121 



them, so as to convert their carcases into a rich 

 manure heap ! Had such been the case, birds would 

 have long ago got used to the device, and have sub- 

 vented it, either by being inured to the poison or by 

 not partaking of the fruit. But the abundance of the 

 Arum shows that its berries are not poisonous to 

 some birds, although they may be to other animals, 

 for thrushes partake of them with safety, although 

 they do not resort to the berries when an abundance 

 of more favourite food is at hand. 



The efflorescence of wax known by the name of 

 *' bloom " on fruits may perhaps be regarded as a 

 protective device, originated for the special purpose 

 of guarding such fruits from decomposition. Rain 

 and dew roll off the surfaces of the fruits covered by 

 "bloom," when otherwise the moisture would not 

 only rot the fruits, but might possibly deposit upon 

 them the germs of microscopic fungi, etc. The 

 general absence of minute vegetable parasites upon 

 them, and the length of time ripe grapes, plums, etc.,, 

 will hang uninjured if their " bloom " is not interfered 

 with, shows how effective this special secretion has 

 proved. Possibly the deposit also prevents the 

 evaporation of the internal juices, and so keeps them 

 looking plump and attractive for a longer period of 

 time than otherwise would be the case. 



Poisons are frequently secreted in the leaves, 

 bark, and other tissues of plants ; but some other 

 chemical deterrent principle is generally employed. 



