790 
Physiology. — “Influence of the seasons on respiratory erchange 
during rest and during muscular exercise’. By Dr. C. J. C. 
van Hoocennuyze and Dr. J. NiEUWENHUYSE. 
(Communicated by Prof. C. ErskmaN in the meeting of October 26, 1912). 
The primary object of our inquiry has been to find out, whether 
muscular exercise increases the metabolism in man as much in the 
cold as in the warm season. 
We have taken the consumption of oxygen as the index of the 
metabolism. 
Since it is still a matter of controversy, whether the seasons in- 
fluence metabolism even during rest, we have thought fit to deter- 
mine also the absorption of oxygen during rest in the same two 
persons, who were subjected to the muscular test. Besides, the gas- 
exchange has also been examined with two other subjects only 
during rest. 
A. Respiratory Gas-exchange during rest. 
In 1859 E. Surru *) presented to the Royal Society of London a 
series of observations upon the influence of different factors (i. a. the 
seasons) on the gas-exchange in man during rest. The amount of 
oxygen consumed was not determined, only that of carbon dioxide 
given off. [f we are to take the latter as a quantitative index of the 
metabolism, SmirH’s experiments would prove that it is more intense 
in the cold months and less so in the warm season. 
EvkMAn?) made similar experiments in 1897 with improved means, 
and moreover measured the quantities of oxygen. As known, the latter 
afford a more reliable index of the intensity of the metabolism. He 
found no difference for the different seasons. 
His opinion that the metabolism is the same in warm and in cold 
seasons is also corroborated by his previous investigations *) made 
in the East-Indies, from which it appeared that the amount of meta- 
bolism of man in the tropics agrees with that of people in our parts. 
1) Philosophical Transactions of the Royal Society of London 1£59 p. 681. 
2) C. EvKMman. Over den invloed van het jaargetijde op de menschelijke stof- 
wisseling. Verslagen van de Koninklijke Akademie van Wetenschappen te A'dam, 
8 Dec. 1897. 
3) C. EvKMman. Beitrag zur Kenntniss des Stoffwechsels der Tropenbewohner. 
Virchow’s Archiv. Band 133. 1893, p. 105. 
Idem. Ueber den Gaswechsel der Tropenbewohner, Pfliiger’s Archiv. Band 64, 
1896, p. 57. 
