Shortly after the chrysalis is formed, the esophagus is discovered to have turn out to be longer and extra slender; the stomach to have decreased drastically, each in length and diameter, whereas the intestine is elongated, and the cæcum terminates in a reasonably distinct rectum. These modifications are more wise when the butterfly is on the purpose of being disclosed, and after that occasion the esophagus could be very lengthy and slender; the sucking-stomach within the shape of a large vescicle; the stomach double; and the intestine very long and convoluted. The remaining portion of the nutrimental canal may be known as the intestine. The intestine commences immediately behind the chylific ventricle, from which it’s separated by an annular constriction or sphincter. This expansive ventricle, after the final metamorphosis, turns into slender, its element elements more distinctly defined, and so much elongated, that the whole digestive tube exceeds from six to twelve times the length of the physique. Within the larva of the carnivorous Coleoptera, as an illustration, that are equally predaceous with the mature insect, the one distinguishable parts of the alimentary canal are the esophagus, a minute crop, a chylific ventricle, and a small intestine-the ventricle being completely smooth externally. The upper wings have three small cubical cells at the base.
It’s discovered to pervade the abdominal cavity, and to penetrate to all of the extremities, with out excepting the antennæ, legs, and wings. Underneath come two white agency formations, mastoid or papillary in kind; and related formations are found within the cuttle-fish additionally, only that they’re of a firmer consistency within the cuttle-fish. After passing by the esophagial tube, the alimentary matter reaches the crop, where it remains for a time, and acquires a softer consistency by imbibing the peculiar juice with which this cavity is replenished. No such conduits as absorbent vessels or veins present in insects, the chyle merely transudes via the parietes of the digestive tube into the cavity of the physique, whence it finds its solution to a large cylindrical canal placed near the back, from which it receives an impulse which conveys it to completely different parts of the physique. As it necessarily follows the contour of the physique, it is normally straightest in larvæ, (notably in caterpillars,) and within the imago it curves downwards between the thorax and abdomen, to enable it to go by the slim isthmus by which these elements are united. To each facet of the abdominal portion of the dorsal vessel, or that which is divided into separate chambers furnished with valves, are attached a number of flat triangular muscles, the factors of that are mounted to the dorsal plate of the abdomen, (Plate III.
↑ “Let nobody that is unacquainted with this examine, suppose that there is any exaggeration in this account; or that what I have associated, is completed with a view to catch the opinion of the public. Removed from it. Every adept is aware of it, and to every adept I would attraction. “I’ve counted above three hundred eggs, contained within the bag of a spider; and I have noticed more than that quantity laid by a water insect (Phryganea) on a blade of grass, by a river side. It extends alongside the again from the head to the anus, mendacity only a short approach beneath the integument, and consequently above the digestive canal, from which it is separated by a layer of fatty matter, (See Plate II. Usually the mother-beetle makes a fairly straight tunnel along which, at brief intervals, she lays her eggs. When very quick the chyme contained in it affords no chyle, as may be noticed in caterpillars; however when of nice length, there’s little doubt that the chyme is additional elaborated, and chyle separated, simply as it was in the chylific ventricle.
Such are the principal parts and appendages of the great alimentary tube wherein digestion takes place. Much uncertainty nonetheless exists with regard to the manner wherein the blood is conveyed to the totally different parts of the body after it is discharged from the guts. If we were completely acquainted with the functions of these organs in insects, as has been judiciously remarked, it is possible that we might discover cause for these numerous divisions, each having a particular perform alloted to it; however in our present uncertainty on this respect, we run much less risk of error by adhering to the extra simple division and nomenclature indicated on a former web page. Pl. II. fig. 5, a, a, represents a big semi-diaphanous glandular piece, (drastically resembling a real gland,) composed of two lobes, the hinder of which is digitated; from each of those issues a really flexuose excretory duct, which debouches into the esophagus, (b, b.) The salivary reservoirs are, on this occasion, slender and twisted, as is very often the case; (c, c.) Cicada orni presents a distinct association, the secreting organs consisting of a mass of minute oval baggage or bladders, divided into two bundles, that are united by means of a tubular canal; (Pl. II.