Abdomen.
3450. The two intestines, namely, the large and small, are more distinct from each other than in other animals; the cæcum coli is in most distinct; the stomach expanded and membranous in texture, so that it operates simply through chemical influence. Liver, pancreas, and spleen occur in all.
3451. The sexual parts are in every respect very perfect. The penis is present in all, and all have an uterus, fallopian tubes, and separate oviducts. The penis is in many still retracted into a cloaca, and the testes frequently lie within the abdominal cavity.
3452. As in the tegument the parts separate and each becomes self-substantial, the fibre animal, the tegument vegetal, and so on even in the sexual animal. The ovarium, consisting of two parts, now also separates, since one becomes animal, but the other remains vegetal. The albumen-organ becomes animal, detaches itself from the sexual parts, is developed in the self-substantial tegument and called mamma.
The Aistheseozoa are thus also Mastozoa or Mammalia.
3453. This separation of the sexual animal is one of the first characters. The mammæ could never be wanting, because they indicate an essential stage in the development. The albumen-organ becomes an organ of sensation. If the existence of mammary organs be doubtful, as in the Ornithorynchus, the hairs are in that case perfectly distinct. No Reptile nor Bird can have hairs, because their covering is derived only from a partial system, the respiratory; while hairs are from the general vascular system, which is the foundation of the tegument, of the sense of feeling. The Ornithorynchus is a furred animal, and this would suffice to bring it among the Aistheseozoa, were we even to deny it mammary organs.
3454. Both sexes, male and female, have breasts. In youth they are most readily detected in the male, because their sexual parts then rank nearer to the female. In other respects the mammæ are probably the chiefest organs of absorption for the embryo.
3455. The mammæ are nobler in rank, when, as udders they become self-substantial; and the more they remove from the belly or abdomen, and come, as breasts, to be placed upon the chest.
D. ORDERS AND FAMILIES.
3456. Had the names been given in strict accordance with rank; then the class-divisions, which correspond to the circles, would have been called Orders.