Restoration of the Silkworm. 155 
little thought how applicable were his observations to the actual 
condition of an insect of such value and importance to his own 
countrymen as the Bombyx Mori. I have italicised those passages 
to which I wish more particularly to draw the reader’s attention, 
and shall now proceed to show their applicability to my present 
subject. 
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 ven- 
tilation 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 soi] 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 unbealthy 
state of the atmosphere in which it is reared, together with an in- 
sufficiently 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 ‘colours and original strength of con- 
stitution. 
Herein consists the entire secret of my experiments with the 
Bombyx Mori. Seeing that a very remarkable difference in 
colour sometimes occurred, and being fully aware of the truth of 
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 
