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Page:Popular Science Monthly Volume 21.djvu/853

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the saline masses that exist in the interior of our globe. Whenever waters of infiltration reach these saline deposits, they dissolve more or less considerable quantities of them, and, when they come out again into the light, they constitute what are called saline mineral waters.



THE fundamental difference in the feeding of plants and animals is conditioned on the presence or absence of chlorophyl. Green plants are competent to assimilate inorganic matter by means of the chlorophyl-bodies in their leaves, while animals require organic substances for food. Were this difference mere comprehensive, it would incontestably be regarded as the most important of all the differences between the two classes of organisms. But there are, on the one hand, plants that have no chlorophyl—the fungi; and, on the other hand, animals which have been known for a considerable time to contain chlorophyl, as the fresh-water sponge (Spongilla), the hydra, several gyrating moners, and many infusoriæ and rhizopods.

The fungi feed, like animals, on organic matters; but it is not yet sufficiently established whether the so-called chlorophyl-bearing animals can be nourished entirely after the fashion of real plants, by the assimilation of inorganic matter; or, in other words, whether, with an abundant access of air and suitable lighting, they can live in filtered water. Before we can approach this question more closely, however, we must decide another equally important one, whether the chlorophyl-bodies present in the animals are really elementary parts, morphologically corresponding with vegetable chlorophyl produced by the animals themselves, or whether they are not unicellular vegetable organisms parasitic in the animals—in other words, it must be decided whether the green bodies in animals are parts of cells or are them-selves cells; whether they are morphologically and physiologically dependent on the tissue in which they appear, or independent of it.

Morphological investigation has been pursued upon hydras, spongillas, a planaria, and a number of infusoria, from which the green bodies have been pinched off and examined with strong magnifying powers. All the examinations of these different objects have given the uniform result that the green bodies of animals are not evenly green like the chlorophyl-bodies of plants, but contain colorless protoplasm besides the green mass, or, at least, a cell-kernel which can be easily distinguished on treatment with hematoxylin. Among them were likewise several cell-kernels, which were regarded as evidences of the beginning of division, for normal chlorophyl-cells never contain a cell-kernel.