424 RESEARCHES UPON FEVER. 



influences the development of animal heat independently of the respira- 

 tory or circulatory centers in the pons. It would seem, therefore, that 

 we must adopt one of the first two theories as the true explanation of 

 the phenomena observed. To decide which of the two is conect is not 

 at present possible. We would naturally expect some distinct altera- 

 tion of blood pressure to follow paralysis of the arterioles of the mus- 

 cles, but the abdominal vessels are so enormous that it is possible that 

 they are the dominating influence in the blood pressure. I am still 

 engaged upon this subject, but what will come out of it is uncertain. 



It having been noticed by Hitzig and other experimenters that wounds 

 of certain portions of the brain cortex near the sulcus cruciatus are in 

 the day followed by rise of temperature upon the opposite side of the 

 body, attention was directed to this region. It was first proven by 

 cardiometrical experiment that such wounds do not affect the general 

 circulation to an appreciable extent. Seventeen caloriinetrical experi- 

 ments were there made. Five with destruction of both Hitzig's regions ; 

 result, average increase of heat production 53 per cent. Seven with de- 

 struction of one Hitzig region ; result, average gain of heat production 

 19 per cent. Five with destruction of other portions of the cortex ; result, 

 in no case increase of the heat production. Then the same region was 

 irritated with salt, and the heat production was found to be lessened. 

 These results certainly are very extraordinary if there be no connection 

 between this cortical region and the production of animal heat. Sup- 

 posing the method of investigation fauliy, the chances of nineteen suc- 

 cessive experiments of different character, aU concurring in their result, 

 would be very small. When it is also borne in mind that these nine- 

 teen experiments are in accord with a long preceding series of com- 

 plicated experiments, and that no exception has been met with, it is 

 plain how small must be the chances of serious error either in the 

 method or result. 



In studying the subject of fever itself, the first question investigated 

 was whether the febrile elevation of temperature be due to increased 

 production, or simply lessened evolution of caloric. The experiments 

 were mostly made upon dogs ; each experiment lasted not less than 

 three days, most of them six days; therm ometrical readings being 

 made every 20 minutes by night as by day. The normal and febrile 

 states were studied, both when food was administered and when it was 

 withheld. The first result was to show that there are two distinct^ va- 

 rieties, so to speak, of animal heat, namely, that derived from the 

 stored-up materials of the body, and that derived from the food ; and 

 that the second factor in the heat production is of great value, although 

 it does not decidedly affect the bodily temperature. After a full meal, 

 the amount of heat developed is enormous ; but it is evolved as fast as 

 produced. In fever little or no food is taken, and consequently this factor 

 disappears. The heat produced at the expense of the stored materials 

 of the body is always excessively increased in fever, and usually more 



