In a little work published by Olivier de Serres, in 1603, under the title of _Cueillette de la Soie_, "The Gathering of Silk," we find a memoir entitled: _La second richesse du mûrier, qui se trouve en son escorce, pour en faire des toiles de toute sorte, non moins utile que la soie provenant d'icelui_, "The second wealth of the mulberry tree which is found in its bark, how to make of it cloth of all sorts, not less useful than the silk derived from this tree." Olivier de Serres proves in this memoir that the second bark, or _liber_, of the mulberry tree contains a fibre capable of replacing hemp or flax, and he describes the processes by which this may be obtained. The processes which had been proposed by Olivier de Serres in 1603, were resumed in the Cévennes a dozen years ago by M. Duponchel on the one hand, and on the other by M. Cabanis,[64] who operated on the bark instead of taking the whole of the wood of the mulberry tree. But none of these attempts have given any good results up to the present moment. [64] See the "Année scientifique," 7e année, p. 432. The various diseases which for the last fifteen years have been so fatal to the mulberry silkworm, have suggested the idea of acclimatising in Europe other silk-producing Bombyces, if not with the view of superseding, at least as auxiliaries to the mulberry species. The genus _Attacus_ has furnished these auxiliaries. Among the species which have, in this respect, the greatest claims to our attention, we must place in the first rank those which feed upon the leaves of the oak tree. Indeed, the trees which can be made use of for their cultivation are very numerous in Europe, and, moreover, the silk produced by these worms appears to possess superior qualities. There are three oak-feeding species of the genus _Attacus_. They are _Yama-Maï_, _Pernyi_, and _Mylitta_. [Illustration: Fig. 221.--Larva of Attacus (Bombyx) Yama-Maï.] The silk of _Yama-Maï_ is as bright as that of the mulberry silkworm, but a little less fine and strong, and occupies the first rank after it. If we could succeed in acclimatising this species it would supply any deficiency there might be in our crops of ordinary silk. The eggs of the _Attacus Yama-Maï_ were brought from Japan--where this worm is reared--conjointly with the mulberry silkworm, in 1862. The larvæ hatched at Paris, in 1863, were green, of a great size, remained in that state eighty-two days, and were easily reared. Their cocoon resembles that of the mulberry species. It is composed of a beautiful silk of a silvery whiteness in the interior, and of a more or less bright green on the exterior. The moth is very large and beautiful, of a bright yellow colour, approaching orange. We give a drawing of the _Attacus Yama-Maï_, taken from the plates which accompany M. Guérin-Méneville's memoir.[65] [65] Sur le Ver à Soie du Chêne, et son Introduction en Europe. Extrait du Magasin de Zoologie, 1855, No. VI.