[123] Plateau has expressed a strong opinion that neither in the stomach of Crustacea nor in the gizzard of Insects have the so-called teeth any masticatory character. He compares them to the psalterium of a Ruminant, and considers them strainers and not dividers of the food. His views, as stated by himself, will be found on p. [131].
[124] See Watney, Phil. Trans., 1877, Pt. II. The “epithelial buds” described and figured in this memoir are also closely paralleled in the chylific stomach of the Cockroach.
[125] These epithelial buds have been described as glands, and we only saw their significance after comparing them with Dr. Watney’s account.
[126] Development shows that these tubules belong to the proctodæum, and not to the mesenteron.
[127] The epithelial bands of the rectum of Insects were first discovered by Swammerdam in the Bee (Bibl. Nat., p. 455, pl. xviii., fig. 1). Dufour called them muscular bands (Rech. sur les Orthoptères, &c., p. 369, fig. 44).
[128] “Lehrbuch der Histologie,” p. 337.
[129] Except in Dragon-flies and Ephemeræ.
[130] Zeitsch. f. wiss. Zool., Bd. XXX.
[131] The contents of the Malpighian tubules may be examined by crushing the part in a drop of dilute acetic acid, or in dilute sulphuric acid (10 per cent.). In the first case a cover-slip is placed on the fluid, and the crystals, which consist of oblique rhombohedrons, or derived forms, are usually at once apparent. If sulphuric acid is used, the fluid must be allowed to evaporate. In this case they are much more elongated, and usually clustered. The murexide reaction does not give satisfactory indications with the tubules of the Cockroach.
[132] Bull. Acad. Roy. de Belgique, 1876.