IXxxiil 
Cynthia, how have the rows of black spots on the larve of the latter become obliterated, 
and the covering of white down on the body of the imago of A. Ricini been acquired ? 
For these black spots are not merely superficial and evanescent marks, which, like the 
white powder on the body of the larva, can be removed, but are actual typical dermal 
marks and colouring of structure, and are no more capable of obliteration than are the 
spots and roses of the leopard and other species. Climate and fvod could exercise no 
influence over such marks, because they are imprinted by nature in the epidermis as 
typical and specific characters, and are always present whether the insect occurs in 
the temperate mountains of Mussooree or under the tropical sun of Assam, precisely as 
are the spots on the leopard, whether found in Southern India or bordering on the 
snows of the Himalaya. Were I to admit that such specific distinctions could be 
obliterated, and others acquired by a change of food, climate and domesticity, it would 
reduce me to the necessity of adopting Darwin’s theory that our present species were 
formerly mere varieties of some types that have died out; while if A. Ricini has im 
truth descended from A. Cynthia and has attained permanent specific characters of its 
own, which is undoubtedly the case, then can it no longer be considered as identical 
with A, Cynthia from which it first proceeded as a variety, and thus on the Darwinian 
principle are the species proved to be distinct, and Dr. Bree’s opinion is again refuted. 
- . . . Experiments instituted in India in 1859, by crossing the wild Himalayan 
| silkworm, Bombyx Huttoni, with the long-domesticated Bombyx Mori of China, 
| €ashmere and Milan, produced the following results. The crossing was reciprocal, 
the wild female pairing with the domesticated male, and the domesticated female with 
the wild male. The coupling of the wild male with the domesticated female was 
effected with the greatest difficulty, and all the eggs thus obtained shrivelled and were 
unproductive. -With regard to the other cross, the difficulty was somewhat less, 
because the domestic males readily and eagerly sought the females, which however 
were shy, and several, though not all, produced eggs. Very few of these however were 
prolific, the greater number, as in the former case, withering and drying. The few 
larve produced from this cross retained all the intractable habits of the wild species, 
and were accordingly placed upon trees in the open air, where in due time they spun. 
In the larva, cocoons, and moths, there was no perceptible difference from the wild 
race. Similar experiments were again tried and carried on even to a second cross with 
the domestic stock, but it was found that, cross as one might, through every stage the 
insect invariably reverted to the wild B. Huttoni, and neither in appearance nor in 
habits at all resembled the domestic species. The wild stock then preponderated, and 
Nature refused to promote the cross. Experiments with B. Mori and B. Creesi, and 
Others with Attacus Cynthia and A. Ricini, produced exactly the same results, Nature 
always favouring the strongest or healthiest species. Hence it is evident that Nature, 
| ‘so far from approving of these intercrossings, has in every case shown a strong dispo- 
‘sition to revert to the most natural or to the strongest species, and that in every 
instance she has succeeded. It may be objected that when, as in my opening remarks, 
I declare that there is no tendency to revert unless the parents are of different species, 
| Dcontradict my former remarks on the reversion and restoration of the silkworm (see 
Trans. Ent. Soc., 3rd series, vol. ii.); this however is not the case, for the object of 
feversion is to cast out something that is unnatural and inimical to a species, so that 
ature, in order tu preserve her types, always endeavours to cast out the effects of a 
oss; and where, as in B, Mori, the constitution of the insect has been destroyed by 
