Fig. 162.—Parts of a vein of the cockroach, showing the nerve (n) by the side of the trachea (tr); c, blood-corpuscles.—After Moseley.
Other histological elements.—These are the blood-lymph, corpuscles, blood-building masses, and nerves. Schaeffer states that in the immature pupal wings we find besides the large tracheæ, which are more or less branched, and in the wing-veins at a later period, blood-corpuscles which are more or less gorged with nutritive material, and also the “balls of granules” of Weismann, which are perhaps the “single fat-body cells” detected by Semper. Schaeffer also states that into the hypodermal fold of the rudiments of the wings pass peculiar formations of the fat-body and tracheal system, and connected with the fat-body are masses of small cells which by Schaeffer are regarded as blood-building masses.
Fine nerves have also been detected within the veins, Moseley stating that a nerve-fibre accompanies the trachea in all the larger veins in the insects he has examined (Fig. 162), while it is present in Melolontha, where the trachea is absent.
LITERATURE ON THE WINGS
Jurine, L. Nouvelle méthode de classer les Hyménoptères et les Dipterès. Genève, 1807, 4º pp. 319, 14 Pls.
—— Observations sur les ailes des Hyménoptères. (Mém. acad. Turin, 1820, xxiv, pp. 177–214.)
Latreille, P. A. De la formation des ailes des Insectes. (Mém. sur divers sujets de l’histoire naturelle des Insectes, etc. Paris, 1819. Fasc. 8.)
—— De quelques appendices particuliers du thorax de divers Insectes. (Mém. du Mus. d’Hist. nat., 1821, vii, pp. 1–21, 354–363.)
Chabrier, J. Essai sur le vol des insectes. (Mém. du Mus. d’Hist. nat., 1820, vi, pp. 410–476; 1821, vii, pp. 297–372; 1822, viii, pp. 47–99, 349–403.) Separate, pp. 328, 13 Pls.
Burmeister, Hermann. Handbuch der entomologie, i, 1832, pp. 96–106, 263–267, 494–505.