We next come to one of the greatest names in Entomology, the celebrated De Geer, who united in himself the highest merit of almost every department of that science. Both as a systematist, anatomist, and physiologist, and as the observant historian of the manners and economy of insects, his Mémoires pour servir à l'Histoire des Insectes are above all praise. His system[1397] is contained in a posthumous volume published in 1778[1398].
This system, though built upon the instruments of flight; in its ternary groups, equivalent to the Orders of Linné, adds likewise the instruments of manducation, and is thus intermediate between that of Linné and Fabricius, who perhaps from the consideration of it might derive the first idea of assuming the last-mentioned organs as the basis of a new method. But, though partaking of both, it is nearer to nature than either; and had its illustrious author laid less stress upon the number and substance of the organs of flight, it would probably have been as near perfection in this respect as most that have succeeded it. But following too strictly these characters, he has been led to place in different Classes, or rather Orders, insects that ought not to have been so separated,—as in the case of the two sections of the Hemiptera, and the Coccidæ. In other respects the whole of De Geer's Mémoires are a storehouse of valuable observations, in which he has furnished many a clue for threading the labyrinth of nature, and given most complete and interesting histories of the whole economy and habits of many tribes and genera,—as of the Trichoptera, Aphides, Ephemerina, &c.
In this latter department of the science a light shone during part of the era we are now considering, which eclipsed every one that appeared before it, and has scarcely been equalled by any one that succeeded it. The date of its first appearance, indeed, was a year before that of Linné's first outline of his Systema Naturæ before alluded to; but it may properly be regarded as belonging to his era, since it did not disappear till some years after that had begun. A volume indeed would scarcely suffice to do justice to the preeminent merits of Reaumur, as exhibited in his admirable Mémoires pour l'Histoire des Insectes[1399]: I must therefore content myself with observing, that in judgement and ingenuity in planning his experiments; in patient assiduity in watching their progress; in the elegance of his language, and the felicity of his illustrations, he has rarely, if ever, been equalled. Every subject that he undertook was thoroughly investigated, and in the true spirit of philosophical inquiry. Every where you see him the same unprejudiced and profound observer, attached to no system, anxious only for truth and the advancement of science. If he has any fault, it is, perhaps, that of being sometimes too prolix; but we must recollect that from the nature of his subject much diffuseness was often necessary to render his meaning clear. A greater objection is his total inattention to all system, except with regard to Lepidoptera and their larvæ[1400], so that it is often difficult to ascertain the insects whose history he gives. But with these exceptions, no observer of nature, who wishes his discoveries to be at once profound and interesting, can copy a better model or one nearer to perfection.
Next to that of Reaumur, the name of his admiring correspondent Bonnet may be mentioned. This great physiologist, though still more deficient in systematical knowledge[1401], was also an admirable observer of the economy and manners of insects. In this sense he became an Entomologist before he was seventeen years of age, in consequence of an impression made upon him by the account of the Antlion in that attractive work the Spectacle de la Nature. From verifying its wonderful history with his own eyes, he entered with enthusiasm upon the study of other insects, his observations on which he regularly communicated to Reaumur. Amongst other interesting inquiries, his experiments on that singular anomaly in nature the generation of Aphides[1402] do him the highest credit, and have set that question perfectly at rest[1403].
In another department of the science this period was distinguished by a work which may almost be deemed a prodigy. I am speaking of Lyonet's admirable treatise on the anatomy of the caterpillar of the Cossus,—a work which will uphold his reputation as long as Entomology shall be cultivated as a science, or the comparative Anatomist be delighted to trace the footsteps of Divine Wisdom in the gradually varying structure of animals. The plates to this publication, executed by the hand of its excellent author, are as wonderful as the work itself; and together, to use Bonnet's words, form a demonstration of the existence of God. It is infinitely to be regretted that the author of this incomparable monument of scientific ardour and patient industry should have died before the full completion of his anatomical description of the pupa and imago of the same insect; of which he had prepared a considerable portion of the manuscript, and engraved upwards of twenty of the plates[1404].
Numerous other writers in various departments of the science appeared during this era; but it would be useless to enter into a particular detail of their works and merits. I cannot however omit noticing, on account of his inimitably accurate and chastely coloured representations of Lepidoptera, Sepp's beautiful Nederlandsche Insecten, in which the whole history of these animals, from the egg to the fly, is described and portrayed. In our own country this era was distinguished by no entomological work of any great eminence. Albin, Wilks, and Harris produced the principal. Gould, however, without having any thing of system, gave an admirable account of English ants, which I formerly noticed[1405].
One of our first poets, the celebrated Gray, was also much devoted to Entomology. From his interleaved copy of the Systema Naturæ, that venerable and able naturalist, Sir T. G. Cullum, Bart. copied the following characters of the genera of insects of Linné, drawn up in Latin Hexameters, which he kindly communicated to me.
Coleoptera.
Alas lorica tectas Coleoptera jactant.