204 Oranges and Lemons of India. 



and help it to scatter its seeds to great distances. It 

 may have done more. Elsewhere I have stated that 

 the oil cells of the leaves of young Citrus seedlings 

 were possibly a disadvantage to them. I have seen 

 pots full of seedlings devoured by the young cater- 

 pillars of the Papilio Erythronius, a butterfly that 

 feeds exclusively on the Citrus leaves. The essential 

 oil glands, however, are, I believe, an advantage to 

 the adult tree in a wild state. The aura of the " petit 

 grain " enables the butterfly to find any Citrus tree 

 readily among other trees, where it may deposit its 

 eggs to be nursed, when hatched, by the Citrus leaves, 

 and eventually, in their butterfly stage, to help it to 

 fertilize its ovary, and thus ensure a crop of seed. The 

 delicious scent of its white flowers, which is more 

 powerful at night, may be only another advertisement 

 for night insects to come and help it in the same 

 direction. It would therefore appear that this inte- 

 resting tree, in the days of battling with its surround- 

 ings of all kinds, became provided with armour against 

 the larger animals ; a strong scent, which is unpalatable 

 to destructive locusts, but agreeable to other insects 

 which help in fertilization ; and brilliant and palatable 

 fruit, attractive both to the eye and palate of birds 

 and other animals. Finally, when the Citrus came 

 under the notice of man, its rapid and further progress 

 to its present finished state was ensured. He may 

 now go on and develop any part of the tree which 

 may suit his purpose such as the essential oil of 

 the leaves, that of flowers or rind ; the thickness of its 

 skin, and the abundance and sweetness of its pulp. 



In certain stages of its past history, instead of the 

 attractive essential oil of the C. limonum vulgaris, 

 there may have been formed a repellent secretion. In 

 the lima of Ceylon (C. hystrix), I found that the rind 



