Page:Popular Science Monthly Volume 84.djvu/579

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He reserves for further consideration "whether the vascular changes are the cause or the effect of the rise of temperature." While the work was published as experiments on animal heat, it is the first clear and decided experimental proof for the vasomotor functions of nerves. The operation had been performed for one hundred and fifty years and the constriction of the pupil of the eye had been noticed, but the increased heat and the dilatation of the arteries had never before been observed. With this experiment, the true knowledge of vasomotor nerves begins.

This discovery caused a great stir in the scientific world and several investigators proceeded to work on the subject independently. Brown-Sequard proposed the correct interpretation of the phenomena that section of the nerve caused a dilatation of the blood vessels and the dilatation allowed increased blood flow which resulted in an increase in temperature and irritability. Bernard held continually that part of the heat effect might be due to the influence of the nerves on the chemical activities in the tissues.

Several years later, working on the submaxillary gland, Bernard observed that the blood coming from the gland was bright red, like arterial blood when the chorda tympani nerve was stimulated, and that it was dark, venous and small in quantity when the sympathetic nerve was stimulated. Thus, he showed that the chorda tympani is a vasodilator nerve causing dilatation and increased blood flow, while the sympathetic is a vasoconstrictor nerve. This effect was shown to be true for other glands. This was the first clear announcement of the presence of vasodilator and vasoconstrictor nerves.

Other lines of work occupied his attention, but the results do not possess such fundamental value as those described above. He worked on the physiological effects of curare, the arrow poison of the South American Indians. Carbon monoxide poisoning was explained as due to a stable combination of the gas with the red blood corpuscles. This explanation was made before respiration had been explained as due to an unstable combination of oxygen with the hemoglobin of the red blood corpuscles. He presented a proof against the spontaneous generation of life when that question was a vital issue in the scientific world. He carried out some work on fermentation opposing Pasteur's views that the living cell is necessary, thus anticipating Buchner's proof by twenty years.

Bernard began work when opportunities for research were scarce and his chosen field was looked down upon and scoffed at, but he