LEPIDOPTERA. 247 



Agriculture on the progress of the cultivation of the Ailanthus, and 

 of the breeding of the silkworm, which was reared in the open air on 

 this tree. He mentions, in his Report, the rapid development of the 

 cultivation of the tree in France, the great number of eggs of the 

 Ailanthus silkworm sold, the foundation of a model silkworm nurser}^ 

 at Vincennes, and, this one great point gained, that they had found 

 out the way of unwinding the silk from the cocoons of the Cynthia in 

 one unbroken and continuous thread. 



Till then European industry had only succeeded in drawing from 

 the cocoons of the Ailanthus silkworm a Hoss silk, composed of 

 filaments more or less short, obtained by carding, and unable to 

 produce, when twisted, anything better than floss, that is to say, 

 refuse silk. It is to the Countess de Vernede de Comeillan, on the 

 one hand, and to Doctor Forgemot on the other, that the merit is 

 due of having obtained an unbroken thread of silk from the cocoon 

 oi Attacus CyiitJiia. 



A monograph on the Ailanthus silkworm appeared in 1866 under 

 the title, " L'Ailante et son Bombyx, par Henri Givelet."* It is a 

 complete account of all the results obtained up to the time, both as 

 regards the rearing of the silkwonn and also as regards the cultivation 

 on a large scale of the Ailanthus, or false Japan varnish tree.t 



The Castor-oil Plant Silkworm {Attacus \Bombyx\ ricmi) is a 

 species very nearly akin to the Ailanthus worm, perhaps only a 

 variety, and comes from India. The silk which it produces is very 

 similar in ever^^ respect to that of the Cyjifkia. The rearing of this 

 worm could never attain to any great importance in France, on 

 account of the necessity there is of renewing the plantations of the 

 castor-oil plant each year. It would, however, afford an additional 

 source of income to the farmers in the south of France, who cultivate 

 the castor-oil plant with a view to selling its seeds, which are much 

 used in pharmacy. 



Nearly allied to the genus Attacus, which furnishes us with all 

 these precious auxiliaries to the mulberry silkworm, are a great 

 number of other species, both indigenous to Europe and exotic, 

 mostly remarkable for their great size, and a few of which are common 

 in this country. 



* In 8vo, avec plans et planches coloriees. Paris, 1866, 



t A work by M. Guerin-Meneville on the same subject, entitled, ''Education 

 des Vers a Soie de TAilante et du Ricin," in i2mo., Paris, i860, may also be 

 consulted. 



[For a full account of successful experiments carried on in England, see Dr. 

 Wallace's essay in The Transactiotis of the \Entomological Society of London, 

 3rd series, vol. v., pt. 2 ; Longmans and Co, — Ed.] 



