

ANIMAL HEAT. 519 



or crura cerebri, sudden death ensues; yet the temperature is but 

 slightly increased. These facts show that the injury of the tuber 

 determines a rise of temperature by some action on the metabolism 

 of the body. (2) When a rabbit is bound down and the respiration, 

 blood-pressure, and pulse are recorded on the kymograph, and the 

 thalamus punctured, then the temperature records its highest point 

 at the time when the respiration, arterial tension, and pulse-rate are 

 falling. 



In a transverse section of the corpora striata, I have seen a tem- 

 perature of 110 F. and the animal die inside of five minutes. 

 Hence we must attribute the regulation of temperature to special 

 thermogenic and thermo-inhibitory centers. 



Thermotaxic Centers. These centers compose the thermogenic, 

 thermo-inhibitory, and thermolytic centers, as the aim of all is to 

 regulate the temperature. 



THERMOGENIC CENTERS. Spinal Cord. Destruction of the 

 spinal cord from the fifth dorsal vertebra down permits the animal 

 to generate as much heat as before the operation. A drug, beta- 

 tetrahydronaphthylamin, when injected by the vein causes a great 

 increase of temperature, but after a section behind the tuber cinereum 

 it fails to cause any rise of temperature. These facts lead to the 

 conclusion that there are no special thermogenic centers in the spinal 

 cord, but that the basal thermogenic centers act through the trophic 

 centers in the anterior cornua. 



Brain. When a normal animal is subjected to heat or cold it 

 regulates its temperature and keeps it at a fixed point. If, however, 

 the spinal cord is separated from the brain, the spinal cord is not 

 able to regulate the temperature at a given degree, but its tempera- 

 ture changes with the temperature of the surrounding air. These 

 facts show also the importance of the thermotaxic centers in the 

 brain in the regulation of temperature. 



As to the medulla oblongata and pons, numerous punctures by 

 a probe two millimeters in width and one millimeter in thickness 

 caused a very slight rise of temperature, which was of a very fugitive 

 nature. Cross-section of the pons is an operation which cuts off the 

 afferent and efferent fibers from the thermotaxic centers anterior to 

 it and permits heat-production to increase without any regulation. 

 If there are any thermogenic centers in the pons, puncture ought to 

 bring out the fact, as it has done for the thermogenic centers located 

 in the basal ganglia. 



Any transverse section behind the crura cerebri or pons simply 





