Nov. 1, 1864.] THE TECHNOLOGIST. 



RESTORATION OP THE SILKWORM. 185 



That the long-continued domestication of the silkworm has tended 

 greatly to deteriorate its original constitution, the numerous diseases 

 to which it is now subject, in every country where cultivated, furnish 

 ample proof. That imperfect ventilation of the rearing houses produces 

 a vitiated and impure atmosphere, highly injurious to health ; that the 

 nourishment derived from the mulberry leaves will be more or less 

 good according to the condition of the tree from which they are 

 gathered ; and that the tree itself will be influenced by the nature of 

 the soil and the temperature of the climate in which it grows, are facts 

 of which every observant cultivator is well aware. 



As with the horse, then, so with the silkworm ; an unhealthy state 

 of the atmosphere in which it is reared, together with an insufficiently 

 nutritious diet, combined with other disadvantages which are incidental 

 to a state of servility or domestication, must sooner or later exercise a 

 very marked effect upon the general health of the animals, and the 

 constitution, being once impaired, will necessarily, by affecting the 

 animal functions generally, not only act upon the skin and colour, but 

 engender debility and disease. 



It is under such circumstances, and when the species threatens to 

 become extinct, that Nature's great guide and ruler, acting for the 

 creature's good, and with a view to the preservation of the species, 

 invariably makes efforts to restore it to its original characteristics, and 

 these symptoms of reversion, if seized and followed up by judicious 

 efforts on the part of man, may enable him, perchance, eventually to 

 cast out disease, and restore the species to its natural colour and original 

 strength of constitution. 



Herein consists the entire secret of my experiments with the Bomhyx 

 mori. Seeing that a very remarkable difference in colour sometimes 

 occurred, and being fully aware of the truth ol General Daumas' remark, 

 that " the colours and the qualities undergo no alteration or admixture 

 except in a state of servitude, and under its influences," I determined 

 to ascertain whether the dark colour of some worms was or was not 

 occasioned by an effort on the part of Nature to revert to the original 

 point at which domestication had commenced, and that it actually is 

 such is proved, not only by the colours remaining permanent in the black 

 race, which they do not in the white race, but by the acquisition of quali- 

 ties which originally belonged to the species, and which the pale-coloured 

 worms do not exhibit. Thus, as the General truly observes, "the 

 recovery of the colour of their first ancestors has caused them to be 

 distinguished by more broadly-defined natural qualities. 



Still further, we gather from the observations of M. Boitard, that, 

 " the blaek worm, which is so often met with in the north of France, 

 is absolutely unknown in Italy ; and yet the eggs, which in France will 

 produce them, are often purchased in Italy." 



Here it is plain, if my views arc correct, that climate tells upon the 

 constitution of the insect even in Euiope, and that in Italy, where the 



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