Page:Jardine Naturalist's library Entomology.djvu/149

Rh parts more distinctly defined, and so much elongated, that the whole digestive tube exceeds from six to twelve times the length of the body. The changes which it undergoes in the progressive developments of a Lepidopteron, (Pontia Brassicæ, the common cabbage-butterfly,) as traced by M. Herold, are principally the following: In the Caterpillar there is a very short esophagus, with salivary vessels appended to it; an extremely large cylindrical stomach, and a short intestine, succeeded by a wide but short cæcum. Shortly after the chrysalis is formed, the esophagus is found to have become longer and more slender; the stomach to have decreased greatly, both in length and diameter, while the intestine is elongated, and the cæcum terminates in a pretty distinct rectum. As the chrysalis becomes older farther changes ensue, and about eight days from the time of its assuming that form, the sucking-stomach can be discerned, and the stomach begins to separate into two portions. These changes are more sensible when the butterfly is on the point of being disclosed, and after that event the esophagus is very long and slender; the sucking-stomach in the shape of a large vescicle; the stomach double; and the intestine very long and convoluted. Analogous changes take place in many other tribes, into the consideration of which we cannot now enter. To what has been said respecting the anatomical features of the great alimentary organ, it may be