Page:Popular Science Monthly Volume 23.djvu/183

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is destroyed, they cease. 5. A cat is etherized, inhaling the anæsthetic slowly and without apparent discomfort in a glass box made for the purpose. The trachea is opened, and a glass tube inserted. This is then connected with a U-shaped tube partly filled with a colored liquid; the effect of the respiratory movements in expanding the lungs is shown by the oscillation of the liquid. 6. With an etherized cat the trachea is connected with a pair of bellows. The medulla is cut and the lungs are artificially inflated with the bellows. In this way the heart is kept beating while the entire ventral wall of the chest is removed and the heart exposed to view. If removed from the body, the heart soon ceases to beat. 7. With a cat, anæsthetized and then pithed, the respiratory muscles are stimulated directly or through their nerves. 8. From an anaesthetized frog the cerebral hemispheres are removed. After recovering from the operation, such a frog may remain for weeks in a stupid condition, neither moving nor feeding voluntarily, although it can swim, balance itself on the edge of a board, and swallow food placed in the throat. It thus approximately exemplifies the life of some idiots. 9. A cat is etherized, and part of the right hemisphere exposed. A light interrupted current of electricity is applied to certain spots, and the invariable response is by definite movements of the limbs of the opposite side. Other regions give no response at all. 10. With an etherized cat the vagus nerves are exposed in the neck. A large needle, with a head of red wax, is passed through the skin and muscles, so that its point is fixed in the heart, the pulsations of which are then indicated by the oscillations of the head. When a somewhat strong interrupted current of electricity is sent through one or both of the nerves, the heart beats more slowly, or stops altogether. The current is stopped, and the pulsations recommence. The nerves are then cut, and the heart beats more rapidly, but the respiratory movements are slowed. In this, as in all other experiments under anæsthetics, the animal is killed before revival.

The significance of these and similar experiments may be ascertained from any physiological treatise or well-educated physician. Only the first and the last can be commented on here. Cilia are minute filaments of protoplasm which, among other localities, cover the surface of the membrane which lines the air-passages. Independently of the will they keep up a rapid lashing movement, more forcible in one direction, so that the dust inhaled with the air is continually swept from the smaller tubes into the larger, and so to the larynx, whence it is voluntarily expelled. If we reflect upon the inevitable consequences of a vacation, or "strike," of these millions of irresponsible "sweeps," we shall feel it well worth while to inform ourselves as to their appearance and mode of action, even though the acquisition of this knowledge costs the lives of many frogs. The last experiment affords some clew to the nervous mechanism through which the action of the heart may be accelerated or retarded, or wholly checked on account of violent physical or mental impressions. Who that has felt his heart "flutter," or "stand still," would not, even in a slight degree, fathom the mystery which still surrounds the relations of our bodily organs to each other and to the mind?

Those who denounce all vivisection as "barbarous" are asked to