PHYSIOLOGICAL OXIDATIONS. 967 



tein on the heat-regulating center. In heat-stroke there is also a 

 rise of body temperature due directly apparently to prolonged 

 exposure to high outside temperature. Here the normal regula- 

 tion again breaks down, but since the rise of body temperature may 

 persist for a long time after the initial cause is removed, it may be 

 explained by assuming that the heat-regulating center has been 

 injured, so that it is unable to exercise its normal control of the 

 balance between heat production and heat loss. Granting the 

 existence of such a regulating center in the corpus striatum, with 

 possibly accessory connections to other basal ganglia of the brain, 

 there remains the question as to whether this center acts upon the 

 heat production and dissipation through a special set of calorific 

 nerve-fibers, or whether its influence is exerted more indirectly 

 through the nervous mechanisms which, as we have seen above, 

 have been utilized to explain the phenomena of so-called physical 

 and chemical regulation. At present it may be said with confidence 

 that no convincing evidence has been furnished for the existence of 

 a special group of calorific nerve-fibers. Most physiologists prob- 

 ably are inclined to believe that the variations in heat production 

 and heat dissipation are controlled through excitation or inhibition 

 of the recognized mechanisms, which may be tabulated as follows: 



f 1 . The sweat centers and sweat nerves. 

 Heat loss j 2. The vasomotor center and vasomotor nerves, 



physical regulation | 3. The respiratory center. 



( 4. The water-content of the blood. 

 Heat production ^ ^' "^^^ motor nerve centers and the motor fibers to the 

 egu a ion |^ 2 fhe stimulating action of food on metabolism. 



But it may well be that the acti\dty of these mechanisms is con- 

 trolled and coordinated through a special heat-regulating center 

 in the brain. It seems necessary to assume the existence of some 

 such device to explain the ahnost constant balance that is main- 

 tained at the set level of the normal body temperature, and the 

 alterations in this level which we witness in the case of fevers of 

 different intensities. 



Theories of Physiological Oxidations. — Lavoisier compared 

 the oxidations in the body to the oxidation of organic substances 

 in combustions at high temperatures. He supposed that the mo- 

 lecular oxygen unites directly with the substances oxidized in one 

 case as in the other. It soon became evident, however, that this 

 direct analogy is not applicable. The material that is oxidized 

 in the body— fats, carbohydrates, proteins— is consumed with a 

 certain rapidity, — in the case of muscular contractions with great 

 rapidity, — and we know that these same materials out of the body 

 at a temperature of 39° C. are oxidized with extreme slowness. It 

 became customary, therefore, to speak of the oxidations in the body 



