The discoveries of Lavoisier, published in 1789, led to a clear understanding of combustion as a process of oxidation, and paved the way for a fuller knowledge of the part played by the oxygen of the air in the chemical reactions going on in the animal body. Lavoisier showed that the oxygen drawn into the lungs with the air breathed was used in the body for the oxidation of certain substances, carbon being transformed thereby into carbon dioxide, and hydrogen into water. Further, he noted that these oxidations were carried forward on a large scale, and he emphasized the importance of oxygen as being the true cause of the varied decompositions taking place in the living body. The larger the amount of oxygen inspired, the more extensive the oxidation, and consequently the rate of respiration as modifying the intake of oxygen served in his opinion as a regulator to control the extent of the oxidative processes. He pointed out that a definite relationship existed between the amount of work done by the body and the oxygen consumed; greater muscular activity, lower temperature of the surrounding air, the activities attending the digestive functions, all seemed to be associated with a greater utilization of oxygen. Oxidation was the pivot around which all the chemical reactions of the body seemed to centre. Lavoisier, however, was not a physiologist, and he was, quite naturally perhaps, led into some errors. For example, he considered that the process of combustion or oxidation took place in the lungs, certain fluids rich in carbon and hydrogen formed in the different organs of the body being brought there for exposure to the inspired oxygen. Further, his views implied a simple and complete combustion, in which complex substances rich in carbon were directly and completely oxidized to carbon dioxide and water, in much the same manner as combustion occurs outside the body. Again, he assumed that the amount of oxygen taken into the lungs determined the extent of oxidation, just as the use of the bellows, by increasing the draft of air, causes the fire to burn more brightly.