720 The Zoologist — April, 1867. 



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 in 

 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 

 priuciple 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, 

 Cashmere 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 e^gs 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 ejrjrs. Very few of ihese however were 

 prolific, the greater number, as in the former case, withering and drying. The few 

 larva; 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 larval, cocoous, and moths, there was no perceptible difference from the wild 

 race. Similar experiments were again tried and carried on even to a second cross wiih 

 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. Croesi, and 

 others with Attacus Cynthia and A. Ricini, produced exactly the same results, Naluie 

 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 thai 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, 

 I contradict 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 

 reversion is to cast out something that is unnatural and inimical to a species, so that 

 Nature, in order to preserve her types, always endeavours to cast out the effects of a 

 cross; and where, as in B. Mori, the constitution of the insect has been destroyed by 

 loug-continued domestication, the effort is to revert from a sickly to a healthier condi- 

 tion, and not to a different species." The remainder of the paper was a criticism of 

 the Darwinian theory of Natural Selection, the writer's views being principally 

 enforced by arguments beyond the province of the Entomological Society. — 

 J. W. D. 



