ANIMAL HEAT. 509 



sleep is taken during the day it does not disturb the period of the maximum, which 

 occurs at about four P. M. According to these experiments, at eleven in the morning, 

 the animal heat is at one of its periods of maximum ; it gradually diminishes for two or 

 three hours and is raised again to the maximum at about four in the afternoon, when it 

 again undergoes diminution until the next morning. The variations amount to from 

 about 1 to 2- 10. The minimum is always during the night. 



The influence of defective nutrition or inanition upon the heat of the body is very 

 marked. John Hunter, in his experiments upon animal heat, made a few observations 

 upon this point and noted a decided fall in temperature in a mouse kept fasting. The 

 same phenomena were also observed by Collard de Martigny ; and Chossat noted the 

 effects of deprivation of food upon the power of maintaining the animal temperature, in 

 the most exact and satisfactory manner. In pigeons, the extreme diurnal variation hi 

 temperature, under normal conditions, was found by Chossat to be 1*3. During the 

 progress of inanition, the daily variation was increased to 5'9, with a slight diminution 

 in the absolute temperature, and the periods of minimum temperature were unusually 

 prolonged. Immediately preceding death from starvation, the diminution in temperature 

 became very rapid, the rate being from 7 to 11 per hour. Death usually occurred when 

 the diminution had amounted to about 30. 



When tiie surrounding conditions call for the development of an unusual amount of 

 heat, the diet is always modified, both as regards the quantity and kind of food; but 

 when food is taken in sufficient quantity and is of a kind capable of maintaining proper 

 nutrition, its composition does not affect the general temperature. The temperature 

 of the body, indeed, seems to be uniform in the same climate, even in persons living 

 upon entirely different kinds of food. The observations of Dr. Davy are very conclu- 

 sive upon this point: "The similarity of temperature in different races of men is the 

 more remarkable, since between several of them whose temperatures agreed, there was 

 nothing in common but the air they breathed some feeding on animal food almost 

 entirely, as the Vaida others chiefly on vegetable diet, as the priests of Boodho and 

 others, as Europeans and Africans, on neither exclusively, but on a mixture of both." 

 Nevertheless, the conditions of external temperature have a remarkable influence upon 

 the diet. It is well known that, in the heat of summer, the amount of meats and fat 

 taken is relatively small, and of the succulent fresh vegetables and fruits, large, as com- 

 pared with the diet in the winter. But although the proportion of starchy matters 

 in many of the fresh vegetables used during a short season of the year is not great, these 

 articles are equally deficient in nitrogenized matter. During the winter, the ordinary 

 diet, composed of meat, fat, bread, potatoes, etc., contains a large amount of nitrogenized 

 substance, as well as a considerable proportion of the hydro-carbons; and, in the sum- 

 mer, we instinctively reduce the proportion of both of these varieties of principles, the 

 more succulent articles taking their place. This is even more strikingly illustrated by a 

 comparison of the diet in the torrid or temperate and in the frigid zone. Under the head 

 of alimentation, we have already noted the prodigious quantities of food consumed in the 

 Arctic regions and the effect of the continued cold upon the habits of diet of persons 

 accustomed to a temperate climate. It is stated that the daily ration of the Esquimaux is 

 from twelve to fifteen pounds of meat, about one-third of which is fat. Dr. Hayes, the 

 Arctic explorer, noted that, with a temperature ranging from 60 to 70, there was 

 a continual craving for a strong, animal diet, particularly fatty substances. Some of the 

 members of the party, indeed, drank the contents of the oil-kettle with evident relish. 



The influence of alcoholic beverages upon the animal temperature has been studied 

 chiefly with reference to the question of their use in enabling the system to resist exces- 

 sive cold. We have already discussed somewhat fully the physiological effects of alcohol, 

 and we have seen that its use does not enable men to endure a very low temperature for 

 a great length of time. This is the universal testimony of scientific Arctic explorers. 



As a rule, when the respiratory activity is physiologically increased, as it is by exer- 



