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Page:Popular Science Monthly Volume 5.djvu/672

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Fig. 4 represents a front view of Paramecium caudatum. He is not an architect, but a wandering, idle sort of fellow, often seen in company with our more staid and settled house-keepers. He gets into the oddest shapes imaginable. If he is a little cramped for room it does not seem to inconvenience him in the least, for his body is so flexible he can make it fat and dumpy, or long and slender, just as the occasion seems to require. If they have any police regulations in this fairy-world, he must be a great trial to the authorities, eluding their grasp, and bowing to them from some other quarter, entirely transformed. But, when there is nothing to interfere with his locomotion, he looks very much like a leaf, as is seen in our figure. He is covered all over with rather short, stiff hairs, or cilia, that look like porcupine-quills—perhaps they are his weapons of defense. He is not carnivorous, but lives on a vegetable diet, and is so transparent that we can always tell what he has taken for his dinner. His favorite food seems to be diatoms. These are beautiful little plants encased in a shell of various forms and colors. This curious animal sometimes manages to swallow two diatoms at once, almost as long as his body, and then he seems rather awkward and stiff, with two great logs on his stomach! But he manages, somehow, to absorb the nutritious, vegetable part of the diatom, and throws aside the beautiful transparent shell, which he has not broken nor injured at all in the operation.


By Prof. JOHN TYNDALL, D. C. L., LL. D., F. R. S., President,

AN impulse inherent in primeval man turned his thoughts and questionings betimes toward the sources of natural phenomena. The same impulse, inherited and intensified, is the spur of scientific action to-day. Determined by it, by a process of abstraction from experience we form physical theories which lie beyond the pale of experience, but which satisfy the desire of the mind to see every natural occurrence resting upon a cause. In forming their notions of the origin of things, our earliest historic (and doubtless, we might add, our prehistoric) ancestors pursued, as far as their intelligence permitted, the same course. They also fell back upon experience, but with this difference—that the particular experiences which furnished the weft and woof of their theories were drawn, not from the study of Nature, but from what lay much closer to them, the observation of men. Their theories accordingly took an anthropomorphic form. To supersensual beings, which, "however potent and invisible, were nothing but a