Rudiments of animal physiology : for use in schools, and for private instruction / by G. Hamilton.

  • Hamilton, George, 1808-1885
Date:
1839
Catalogue details

Licence: Public Domain Mark

Credit: Rudiments of animal physiology : for use in schools, and for private instruction / by G. Hamilton. Source: Wellcome Collection.

Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.

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    opposed to each other, like workmen in a saw-pit. We have thus a set that bends the limbs, and a set that extends them ; sets that lower the body or head, and sets that raise them up ; and it is even in the same manner that the mouth is kept in the centre of the face. When palsy affects the muscles on one side of the face, those opposite, having no counterbalancing power, draw the mouth to that side. 142. It is exceedingly interesting to note the many modes nature employs to accomplish progressive motion among the Vertebrata—making use of two legs in man, four in quad- rupeds, the legs and tail in the kangaroo, the tail in fishes, &c. «&c. We can say only a few words as to her greatest achieve- ment in locomotion, that of flight—a feat which it has foiled all man's ingenuity to imitate. When an animal has to pass rapidly through the air, nature seems to have bestowed her cliief care upon two circumstances; 1st, to lighten the whole fabric as much as possible, which is principally accomplished by making the solid parts thin and hollow, at the same time that the whole body is filled with air like a sponge. Thus, the skeleton of a pelican, five feet long, was found to weigh only twenty-three ounces. And, 2dly, by concentrating the muscular power in those parts that are to be the chief instru- ments of motion. The two pectoral muscles which move the wings of the swallow, have been estimated to possess more power than all the others in the body put together. A flap from a swan's wing has been known to break a man's leg, and a similar blow from an eagle has been instantly fatal. This great power will appear absolutely indispensable, when we consider that a swallow, as well as many bu-ds of prey, will probably often pass through not much less than 1000 miles daily. All the functions, indeed, contributing to locomo^ tion, exist in the highest intensity in the bird. Its skeletonj of all animals, is the most highly ossified; its muscles act with the greatest energy; its blood, to support this energy, is richest in red globules, and the respu-ation, to arterialise the blood, in it alone is double. 143. Perhaps no ordinary circumstance has so much influence on the general health, as due attention to the state of the mus- cular system. We may be convinced of this in two ways; for, 1st, we see persons, whose system no means can prevent continually running mto disorder, evidently because they persist in leading an indolent, inactive, or sedentary life, in which the exercise of the muscles is totally neglected; and, 2dly, we see others, who ne- glect almost all the rules considered essential for securing health except this, that they incessantly exercise their bodies in the open air, and who yet pass through life almost without a bodily
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