Pulmonary Gases in the Respiration of Man. 217 



Mr. Smith while fasting ; hence, in his case, the experiments show the 

 influence of food on the interchange of pulmonary gases. I regret 

 that in the present inquiry no experiments were made on myself 

 while fasting, and that those, fasting, on Mr. Smith are too few to 

 show any influence of temperature under this condition. It would 

 have been, of course, more satisfactory to eliminate the influence of 

 food while inquiring into the action of differences of temperature on 

 the interchange of the pulmonary gases. The results obtained show 

 the effects of a change of temperature on the chemical phenomena of 

 respiration to vary somewhat with different persons, some being more 

 disposed than others to react against an accession of cold by an 

 increased production of carbonic acid. In my case, the effect is very 

 obvious, as seen in the following table (p. 218). 



First of all, if the means of the oxygen consumed per minute, the 

 carbonic acid produced, and the oxygen absorbed, also per minute, be 

 compared with the corresponding figures obtained under the influence 

 of food in my former inquiry,* thej will be found to harmonise with 

 them in a marked degree ; they are as follows : 



In former Obtained 



paper. recently. 



Oxygen consumed 248 c.c. 247 c.c, 



Carbonic acid produced ... 218 ,, 212 ,, 



Oxygen absorbed 30'2 357 



The oxygen consumed is nearly exactly the same in both cases, 

 varying by only 1 c.c. The carbonic acid produced is a little lower 

 in the recent experiments, and the oxygen absorbed somewhat 

 higher. 



The slight difference between the carbonic acid produced in each 

 set of experiments, and also the difference, which is rather greater, 

 between the figures found for oxygen absorbed in the two series of 

 experiments, 30*2 and 35'7, are probably owing to the precaution taken 

 in the recent inquiry of allowing half an hour's perfect rest, in the 

 recumbent posture, before commencing the experiment. Formerly 

 the time of rest had been limited to from five minutes to a quarter of 

 an hour, when the pulse and breathing had become perfectly regular ; 

 but it was subsequently found that half an hour at least should be 

 allowed before collecting the air expired for analysis, in order to 

 ensure the body being in a perfect state of rest. 



The table has been disposed in a graphic form, the curves showing, 

 at a glance, the influence of temperature on the interchange of 

 pulmonary gases in my case ; this influencef may be summarised as 

 follows : 



* ' Koy. Soc. Proc.,' June, 1891, vol. 50. 



f The influence of cold or heat in the present experiments applies exclusively to 



