MOUTH- AND NOSE-BREATHING, BENEDICT APPARATUS. 173 



This comparison does not give such satisfactory results as have 

 been obtained in the preceding comparisons. A general discussion 

 of the use of the Douglas apparatus will be found in a subsequent 

 section of this report. 



MOUTH- AND NOSE-BREATHING WITH THE BENEDICT RESPIRATION APPARATUS 

 (TENSION-EQUALIZER UNIT). 



During the development of the tension-equalizer type of the Bene- 

 dict respiration apparatus, the subject breathed through the rubber 

 mouthpiece. After the pneumatic nosepieces were devised, either the 

 mouthpiece or the nosepieces were used according to the preference of 

 the subject, the majority of the experiments being carried out with the 

 nosepieces. It was accordingly important to know whether the respi- 

 ratory exchange when the subject breathed through the mouth differed 

 from that when he breathed through the nose, i. e., when the mouth- 

 piece was used rather than the nosepieces. Several experiments were 

 therefore carried out at different times to study this particular point. 

 They were distinctly comparison experiments in that the conditions 

 were the same in all of the periods except for the change in the method 

 of breathing. 



The rubber mouthpiece and noseclip were those which are com- 

 monly employed with the Zuntz-Geppert apparatus; the nosepieces 

 were the pneumatic nosepieces regularly used with the Benedict uni- 

 versal respiration apparatus. In nearly every experiment a series of 

 periods was first carried out with one type of breathing, this series 

 being followed by a second series of periods with the other type of 

 breathing. The pulse-rate was determined with the Bowles stetho- 

 scope. The respiration-rate was secured from a pneumograph fastened 

 around the chest of the subject, but in some of the experiments the 

 graphic record was obtained by means of a side-tube connected with 

 the three-way valve (see m in fig. 5). If a manometer were con- 

 nected to this tube, it would show oscillations in pressure corresponding 

 to the inspirations and expirations of the subject. Instead of using a 

 manometer for this purpose, a tambour and kymograph were con- 

 nected, the movements of the pointer on the tambour giving a graphic 

 record of the respiration. In the experiments in 1911, a graphic record 

 of the muscular activity was obtained by means of a pneumograph 

 placed about the hips of the subject. All of the subjects were mem- 

 bers of the laboratory staff and were therefore more or less accustomed 

 to respiration experiments of this kind. The statistics of the nine 

 experiments are given in the following pages. 



STATISTICS OF EXPERIMENTS. 



J. J. C, November 5, 1910. — Mouthpiece, 3 periods; nosepieces, 3 periods; 

 preliminary period, about 1 hour 55 minutes; mouthpiece and nosepieces 

 alternated. Mouthpiece held in place by rubber bandage secured with an 

 elastic strap passed around the head and fastened at the back with a buckle. 



