348 



RESPIRATION. 



A strong infusion of tea has, according to 

 Front, an effect similar to alcohol. 



According to Dr. Fyfe, when a person has 

 taken mercury or nitric acid for some time, the 

 quantity of carbonic acid is diminished. 



Conditions of the mind. Prout found that 

 anxiety and the depressing passions diminish 

 the percentage of carbonic acid in the expired 

 air ; and Vierordt, on two occasions, observed 

 this effect, for a short time at least, from 

 mental emotions, both of a joyful and of an 

 opposite nature. Scharling remarked that in 

 those persons who felt very anxious on being 

 enclosed in the box used by him in his expe- 

 riments, the evolution of carbonic acid gas 

 from the body was much diminished. 



Exercise. Prout states that moderate ex- 

 ercise, as walking, seems always at first to 

 increase the evolution of carbonic acid, but 

 when continued it ceases to produce this 

 effect, and when carried the length of fa- 

 tigue the quantity is diminished : that violent 

 exercise appears to lessen the quantity from 

 the first, or if any increase occurs, this is 

 trifling and transitory ; and that, after violent 

 exercise, the quantity is much lessened. In 

 Prout's mode of experimenting, the percen- 

 tage of carbonic acid having been alone ascer- 

 tained, we have no certain means of judging 

 of the changes in the absolute quantity of 

 carbonic acid evolved, as the increase in the 

 number of respirations and in the bulk of the 

 air respired, occasioned by exercise, was not 

 taken into account. In the experiments of 

 Seguin and Lavoisier already referred to, it 

 was found that Seguin, when fasting and at 

 rest, vitiated in the hour 1210 cubic inches of 

 oxygen gas : by an amount of exercise equal 

 to raising 15 Ibs. to a height of 613 feet, this 

 was increased to 3200 while still fasting, and 

 to 4600 cubic inches, while digesting food. 

 In Scharling's experiments, where the absolute 

 quantity of carbonic acid gas evolved from the 

 whole body in a given time was ascertained, 

 the quantity of carbonic acid was increased 

 during exercise. Vierordt ascertained that 

 during the increased respiratory movements 

 occasioned by moderate exercise, that on an 

 average there was an increase per minute of 

 18'978 English cubic inches in the expired 

 air, containing an increase of 1'197 cubic inch 

 of carbonic acid gas, giving, however, an in- 

 crease of carbonic acid gas in the expired air 

 of only 0'140 per cent. There can, therefore, 

 be no doubt that the evolution of carbonic 

 acid gas from the lungs can be considerably 

 increased by exercise.* 



Temperature. The effects of low tempera- 

 tures upon the respiratory process, as ascer- 

 tained by Spallanzani and Treviranus upon 

 snails and insects, by Marchand upon frogs, 

 and "by different observers upon the hyber- 

 nating warm-blooded animals, are not appli- 



* G. R. Treviranus (Zeitsclivift fur Physiologic, 

 vierter band, S. 29. 1831) and Newport (opera tit.) 

 in their experiments upon insects, observed a mark- 

 ed increase in the exhalation of carbonic acid gas 

 in these animals during active voluntary move- 

 ments. 



cable to the human species, since the re- 

 duction of the temperature to a certain 

 extent induces in these animals a lethargic- 

 condition, well known under the term hy- 

 bernation, altogether different from its effects 

 upon man and the other warm-blooded animals. 

 Seguin and Lavoisier state that in their ex- 

 periments, Seguin, in a temperature of 82 

 Fahr., fasting and at rest, consumed, in the 

 space of an hour, 1210 French cubic inches of 

 oxygen ; while in a temperature of 57 Fahr., 

 he consumed in the same time 1344 cubic 

 inches.* Crawford -f-, in experiments upon 

 guinea-pigs, ascertained that these animals, in 

 a given time, deteriorate a greater quantity of 

 air in a cold than in a warm medium. The 

 most perfect experiments on this point, at 

 least on the human species, are those of 

 Vierordt.J He ascertained, by numerous 

 trials upon himself, the effects of temperature 

 from 37'4 to 75'2 Fahr. From a table, 

 showing the results obtained, both upon the 

 respiration and the pulse, at each degree of 

 the centigrade thermometer within the limits 

 mentioned, he has constructed the following 

 shorter table, where the first table is arranged 

 in two divisions, the one containing the aver- 

 age of all the lower, and the other the average 

 of all the higher temperatures. In the follow- 

 ing table the measures of the expired air and 

 carbonic acid have been reduced to English 

 cubic inches. 



The experiments of Letellier on warm- 

 blooded animals agree in their results with 



* Memoires de 1' Academic Royale for 1789. 



j- Experiments and Observations on Animal Heat, 

 p. 311315. 2nd edit. 1788. 



J Wagner's Handwb'rterbuch, band ii. S. 878, 

 879, und 880. Physiologic des Athmens, S. 73 82. 



Comptes Rendus, torn. xx. p. 795. 1845. An- 

 nales de Chiinie et de Phys. torn. xiii. p. 478. 1845. 

 Letellier has thrown the results of his experiments 

 into the following table. He does not state whether 

 lie measured the temperature by Reaumur, or the 



