Page:Evolution of Life (Henry Cadwalader Chapman, 1873).djvu/22

20 forms, such as the Flying Lemur. There are many similar examples: the Aye-Aye (Cheiromys) has teeth like a rat, while in other respects it is a monkey. The Duck-bill Platypus of Australia (Ornithorhynchus) combines the organization of lizard in its breast-bone, crocodile in its ribs, and bird in the skull and digestive apparatus, and yet is a four-footed animal.

In modern times, through the assistance of the microscope, many minute beings have been discovered which have been successively classified as plants or animals, according to the botanical or zoological tendencies of their describers. As these microscopic beings present the life of both plant and animal at different stages of their existence, it is quite impossible to say to which kingdom they belong. Many naturalists are, therefore, agreed to consider them as a something apart, an intermediate original kingdom, out of which the plant and the animal worlds have been evolved. If life has been gradually developed, and there has been a progress from beings of low organization to higher, it is natural that such a kingdom should exist, partaking in its nature of animal and plant characters. The origin of life is to be sought, therefore, in this main root, of which animals and plants are the rising diverging branches. The beings of this animal-plant kingdom which still exist are only the descendants of a larger kingdom long since extinct, or perhaps some of the most simple are still formed through spontaneous generation.