SILK-PRODUCING INSECTS. 25 



diarrhoea, dropsy, and some other diseases are gene- 

 rally caused by want of attention on the part of the 

 owners of silkworm establishments. 



A remarkable improvement has lately been 

 effected in the breed of the common silkworm 

 (Bombyx mori) by M. Andre Jean, the director of 

 a large silkworm establishment at Neuilly, near 

 Paris, which I had occasion to visit not long ago. 

 This gentleman having communicated his discovery 

 to the Socitte d' Encouragement,* I was invited with 

 M. Dumas to witness the effects of his experiments. 

 A favourable report was afterwards made upon 

 the subject to the Paris Academy. The whole 

 secret consists in causing the largest and finest male 

 and female silkworm moths to breed together. For 

 this purpose M. Andre Jean places aside for breed- 

 ing the cocoons which have been spun by the 

 largest caterpillars, and which have a greater weight 

 than the others. From this sorting of the cocoons 

 a very valuable race of silkworms had been created 

 when I visited the establishment, and the inventor 

 is now occupied in distributing the eggs of this new 

 race among the large silk-breeding establishments 

 of France. The Iarva3 that are developed from 

 these eggs astonish us by their size when compared 

 with the common silkworm. 



* See " Bulletin de la Societe d'Encouragement," Paris, 1856 ; 

 and the journal "Cosmos," Paris, 1856. 



