INFLUENCE OF SLEEP. 363 



belong to the class of substances which are capable of contributing 

 towards the maintenance of the vital functions. We see this, for 

 instance, in the case of alcohol, which when taken with the food 

 diminishes the pulmonary exhalation instead of augmenting it. 



Vierordt, like Prout, found that the excretion of carbonic acid 

 is both absolutely and relatively diminished even after a moderate 

 use of spirituous drinks. He has also confirmed Prout's observa- 

 tion, that the increased excretion of carbonic acid which accom- 

 panies digestion was considerably checked by the use of spirits. 

 Strong tea exerts, according to Prout, precisely the same result 

 on the respiration as spirituous drinks. 



Sleep occasions a very considerable diminution in the excre- 

 tion of carbonic acid, as we learn chiefly from the experiments of 

 Scharling ; thus, for instance, a man who during the day imme- 

 diately after dinner expired 33'69 grammes, exhaled only 22*77 

 grammes in one hour during the night ; in the case of another 

 man, the ratio of the carbonic acid exhaled during sleep in one 

 hour in the night to that eliminated in one hour in the day after 

 dinner, was 31 '39 : 40' 74. In experiments on wood-pigeons, I 

 found* that 6*156 grammes of carbonic acid were on an average 

 exhaled during one hour in the morning by 1000 grammes 5 weight 

 of birds, whilst the same birds expired only 4 4 950 grammes hourly 

 in the night. 



Regnault and Reiset have made observations on the relations 

 of respiration during the hybernation of marmots, which exhibit 

 an enormous difference, compared with the waking state of these 

 animals; thus, for instance, 1000 grammes 5 weight of marmots 

 absorb in their sleeping state from 0'040 to 0'048 of a gramme of 

 oxygen hourly, whilst in their waking state they consume from 

 0*774 to 1*198 grammes. In the sleeping animals only 56'7-J- of 

 the absorbed oxygen pass into the carbonic acid, whilst in the 

 waking state the quantity amounts to about 73$. In two of the 

 three experiments, these observers found that the marmots in their 

 hybernating state exhibited a considerable absorption of nitrogen, 

 whilst they exhaled nitrogen like other animals when in their 

 wakeful state. As a large part of the absorbed oxygen remains in 

 the body of the sleeping animals (since only a small quantity is 

 expended in the formation of carbonic acid, and the water which is 

 formed does not evaporate, owing to the low temperature of the 

 animal), and nitrogen is absorbed, we have an explanation of the 



* Jahresber. der ges. Medicin. 1844, S. 39. 



