THE TEMPERATURE OF THE BODY 



1311 



direction. Thus exposure to cold increases and to heat diminishes 

 muscular metabolism and the heat production of the body. 



The effects of variations in the external temperature on the meta- 

 bolism of warm-blooded animals are well shown in the experiment, 

 from which the following Tables are taken, on the C0 2 output in the 

 ornithorhynchus and in the rabbit (Martin) : 



1. ORNITHORHYNCHUS. WEIGHT, 693 GRM. ; SURFACE, 876 SQ. CENTIMS. 



2. RABBIT. WEIGHT, 750 GRM. 



In the former animal, where the regulation of the temperature of 

 the body is effected almost entirely by changes in heat production, the 

 effect of warming the environment of the animal on the C0 2 output 

 is extremely marked. It will be noticed that the C0 2 per hour sinks 

 continuously with rising temperature up to 32 C. When the tempera- 

 ture of the chamber was raised to 35 the temperature of the animal rose 

 considerably, i.e. the regulatory mechanism was failing, so that the 

 same effect was produced on metabolism as is observed in working with 

 cold-blooded animals. The same change, though less marked, is 

 observed on exposing the rabbit to a gradual rising temperature. 

 Here, however, the process of regulation is aided by alterations 

 in the heat lost as well as in the heat production (Fig. 543). If the 

 animals be observed, whilst subjected to changes of temperature, 

 it will be evident to any one that the regulation is associated with 

 changes in muscular activity. At 30 to 35 C. the animals will lie 



