1879.] Various Attitudes on the Island and Peak of leneriffe. 227 



The experiments of Edward Smith,* show that more carbonic acid 

 is expired by man in summer than in winter. Vierordtf finds that a 

 change of temperature, equal to 10° F., alters the amount of carbonic 

 acid expired by 0183 per cent., increasing it to that amount by a 

 fall, and raising it .by that figure through an increase. These 

 observations were made under temperatures ranging between 38° "7 

 and 75°*7 F. 



Letellier ;£ in 1845, investigated the action of low and high tempera- 

 tures on the production of carbonic acid in the animal body. Animals 

 were made to breathe under a glass receiver during periods varying* 

 from half an hour to several hours. The results are stated in tables 

 which show generally that at the temperature of 32° F., the carbon 

 burnt is twice as great as at 86° F., while at the ordinary temperature 

 intermediate figures are obtained, there being at times an increase 

 and at others a falling off in the amount of carbonic acid formed. 

 This applied equally to a canary bird, a dove, two mice, and a guinea- 

 pig; there was, however, a peculiarity with respect to two of the guinea- 

 pigs. Out of three experimented upon, ISo. 1 yielded at high and 

 low temperatures 1*457 C0 2 and 3*006 C0 2 respectively, or nearly 

 in the proportion of 1 to 2, while with guinea-pigs Xos. 2 and 3 the 

 proportion of carbonic acid expired was 1 to 1*5 or 1'4, instead of 1 

 to 2. In these cases, however, both animals had been clearly very 

 uncomfortable under the high temperature, and one died. The sur- 

 vivor's temperature had risen by 3° and that of the other by 5° "5. But 

 the circumstance perhaps most worthy of notice, as Letellier expresses 

 it, is that heat which the author finds under ordinary circumstances 

 to reduce the formation of carbonic acid in the body, no longer 

 exerted the same influence at night on a dove submitted to experi- 

 ment. That bird at the ordinary night temperature would have 

 given 0*264 grm. C0. 2 , but on raising the temperature to between 

 86° F. and 104° F., it could not be made to exhale less than 

 0*284 grm. This observation is very curious, especially considering 

 that light, according to Moleschott, shows a marked influence in 

 promoting the formation of carbonic acid and darkness in checking it. 

 I do not find that this experiment was repeated, still, if even the only 

 one of its kind, the result is remarkable. 



We now come to the interesting experiments of Moleschott§ made 

 in 1855, on the influence of light on the production of carbonic acid 

 in animals. Frogs were submitted to experiment ; he found that 100 



* " Pfrri. Trans.," 1859. 



f " Pliysiologie des Athenens," 3 845, and " Brit, and Foreign ITed. Beview," 

 1846. 



% Letellier, " Annales cle Chimie et de Physique," Avril, 1845. 

 § T. Moleschott, " Wittelhofer "Wiener Medicinische Wochensclirift," 1855, and 

 " Comptes Eendns de l'Acad.," t. 41, 1855. 



