. Animal and vegetable physiology considered with reference to natural theology. Natural theology; Physiology; Plant physiology; Biology. 13() THE MECHANICAL FUNCTIONS. The material of which the fleshy portion is com- posed is of so tender and gelatinous a nature that the slightest pressure is sufhcient to tear it asunder, and allow the fluid parts to escape; and the whole soon melts away into a thin gelatinous liquid. When ex- amined with the microscope, the soft flesh is seen to contain a great number of minute grains, dis- seminated through a transparent jelly. Every part of the surface of
. Animal and vegetable physiology considered with reference to natural theology. Natural theology; Physiology; Plant physiology; Biology. 13() THE MECHANICAL FUNCTIONS. The material of which the fleshy portion is com- posed is of so tender and gelatinous a nature that the slightest pressure is sufhcient to tear it asunder, and allow the fluid parts to escape; and the whole soon melts away into a thin gelatinous liquid. When ex- amined with the microscope, the soft flesh is seen to contain a great number of minute grains, dis- seminated through a transparent jelly. Every part of the surface of a living sponge (as may be seen in Fig. 53) presents to the eye two kinds of ori- iices; the larger, having a rounded shape, and generally raised margins, which form projecting. 55 papillae; the smaller, being much more numerous, and exceedingly minute, and constituting what are termed the pores of the sponge. It was, for a long time, the received opinion among naturalists that this superficial layer of gela- tinous substance is endowed with a considerable power of contractility : it was generally believed that it shrunk from the touch, and that visible tre- mulous motions could be excited in it by punctures with sharp instruments, or other modes of irritation. These notions are of very ancient date, for they may be traced even beyond the time of Aristotle; and they have been handed down by succeeding. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Roget, Peter Mark, 1779-1869. London : W. Pickering
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