The work of Claude Bernard on the vascular nerves is very important, but his best known contribution to physiology is the concept of homeostasis.
About the same time the famous German experimentalist, Karl Ludwig, invented the kymograph, an instrument that allowed physiologists to record bodily functions in a continuous manner. Ludwig also discovered the depressor nerves. An explanation for their function had to wait for Otto Loewi's discovery of "vagusstoffe", or acetylcholine, in the next century, the parasympathetically-released substance that inhibits the beating of the heart.
Also, about this time, Adolph Fick discovered a means of measuring cardiac output by measuring oxygen consumption - the Fick equation. The same methods are used today in the hospital, but cold saline is used as the dye.
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