CHAPTER VII. 



THE INFLUENCE OF PHYSICAL FACTORS UPON THE RESPIRATORY 



EXCHANGE. 



The Influence of Temperature. 



A VERY large number of experiments have been made on the influence 

 of temperature upon metabolism both in cold-blooded and in warm- 

 blooded animals, but comparatively few of them have been made under 

 standard conditions. In most, the animals have been free to move 

 about and even in cases where they have been tied, muscular move- 

 ments have not been prevented or muscular tone abolished. In these 

 conditions a fundamental difference has been observed between the 

 effects of temperature upon cold-blooded and upon warm-blooded 

 animals. 



COLD-BLOODED ANIMALS. 



In cold-blooded animals the respiratory exchange almost always 

 rises with increasing temperature, but generally irregularly and to a 

 very different degree in different animals. Experiments have been 

 made among others by Regnault and Reiset [1849] on Lacerta, by 

 Jolyet and Regnard [1877] on fishes, by Schulz [1877] on frg s > 

 by Vernon on a large number of terrestrial [1895, 1897] and 

 marine [1896] animals, by Konopacki [1907] on the earth-worm, by 

 Martin [1902] on the reptile Cyclodes gigas, by Slowtzoff [1909] on 

 insects, by Battelli and Stern [1913] on insects, by Knauthe [1898] on 

 fishes, by Montuori [1913] and by Lindstedt [1914] on different aquatic 

 animals, by Marie Parhon [1909] on bees. 



Vernon's experiments [i 897], which are probably the most complete, 

 consisted in series of determinations made on the same animal or 

 group of animals both at increasing and decreasing temperatures be- 

 tween 30 and 2. Each temperature at which a determination was 

 made was maintained constant for fifteen to thirty minutes. The Hal- 

 dane air-current apparatus was employed. As seen from the table in 

 which the results are given in mg. CO 2 per kilogram and hour and in 

 which averages of several such series with each species are given, differ- 

 ences were observed between the gas exchange with rising and falling 

 temperature. The results obtained with rising temperature are in each 



case given first. 



8 4 



