Introduction to Entomology; Comprehending a General View of the Metamorphoses, External Structure, Anatomy, Physiology, and Systematic Arrangement of the Class Insects (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1840. Excerpt: ... ANATOMY AND PHYSIOLOGY OP INSECTS. Having thus traced the progress of insects from the time of their hirth till they arrive at their full maturity, and likewise noticed the most remarkable features in their external conformation, it now becomes requisite to advert to their internal structure, and give a comprehensive view of the complex system of organs by which life is maintained. In these a very close analogy, for the most part, exists to the vital system of the higher animals; but in some respects curious and most important differences prevail. Viewing the animal kingdom as forming a progressive series, from the most simple to the most complex organism, insects may be regarded as occupying nearly the centre of the scale; for, though some properties might entitle them to rank higher, there are others in which they are so deficient, as completely to counterbalance that consideration. In muscular vigour, for example, and the complication of the digestive canal, they are almost equal to the vertebrata, while the circulating system is so imperfect, that it was, till lately, a matter of doubt whether it deserved the name. From these considerations, it may be inferred that the systems of organs are neither very complex nor very simple, and that in these respects, there is some degree of inequality among them. They may be considered, together with their respective physiological functions, under the following heads: 1. Nutrition; 2. Sensation; 3. Muscular System; 4. Reproduction. Nutrition.--As nutrition consists in the renewal of the molecules which constitute an animal body, and as that is accomplished by means of the food, we have only to consider the principal processes which the latter undergoes, in order to obtain an indication of the different heads unde...