262 ON AILANTHINE. 



cocoon, the kind of silk, and the characterizing marks of the moth 

 itself pronounce them at once to be the same animal. But how have 

 these animals acquired such different habits and tastes ? This can 

 only be explained upon the supposition that a long- period of hard- 

 ening in a temperate climate like the province of Shan Tung 

 would produce in course of time a more hardy progeny, ieed- 

 ing habitually on a common plant of the country ; while the more 

 natural and more effeminate brood of Central India, preferred as 

 food the leaves of a plant which will only flourish in warm lati- 

 tudes. Unless specific distinctions exist it is clearly a bad plan to 

 -distinguish an insect from the peculiar plant it eats, for this may 

 ■be a simple point of preference, — if it cannot get the one it 

 will eat the other and thrive on it ; besides a long period of hard- 

 ening will often enable an animal to live and thrive on a vegeta- 

 ble very different from its native food. We need only example 

 the ordinary Bombyx Mori or common silk worm, the finest varie- 

 ties of which, after passing a year or two in our climate, will live, and 

 thrive, and spin beautiful silk on the common lettuce. Of the 

 tree on which the ailanthus worm feeds it may be necessary here 

 to speak shortly ; we shall have to describe the animal itself more 

 fully afterwards. 



It appears that the tree was originally introduced into this coun- 

 try by the abbe d'Incarville, in 1751, as the " Vernis de Japon" 

 tree, or that which yielded the famous Japan or China varnish. 

 This turned out, however, to be a mistake, as the true Japan varnish 

 tree has since been introduced into Europe. Since this latter 

 introduction the Ailanthus glandulosa has been known as the false 

 varnish tree. It is a hardy plant in our climate, standing severe 

 winters well, and producing an abundant crop of leaves especially 

 from young shoots in early summer. It has no especial partiality 

 for particular varieties of soil, thriving as well and producing as 

 abundant a crop of leaves in the most barren soil as in the richest 

 loam. It seems equally indifferent, too,as to the characteristics of the 

 atmosphere in which it lives, healthy young trees being observable 

 in the squares and smoky environs of London. The advantages 

 of a plant such as this in the rearing of a hardy animal on its foli- 

 age need not be pointed out. Throughout France generally this 

 tree flowers and seeds freely, and the seed sprouts and grows read- 

 ily in Great Britain ; but in addition to this method of propagation, 

 another exists in the roots, which if cut into pieces like the potato 

 spring forth and grow luxuriantly ; no plant indeed can be more 



