1 68 



NUMBER OF RESPIRATIONS. 



the higher the surrounding temperature, but this result only occurs when the actual tempera- 

 ture of the blood is increased, as in fever. 



(5) Digestion. There is a slight variation during the course of the day, the increase being 

 most marked after mid-day dinner ( Vierordt). 



(6) The Will can to a certain extent modify the number and also the depth of the respira- 

 tions, but after a short time the impulse to respire overcomes the voluntary impulse. 



(7) The Gases of the Blood have a marked effect, and so has the heat of the blood in fever.] 

 [(8) In Animals 



[(9) In Disease. The number may be greatly increased from many causes, e.g., in fever, 

 pleurisy and pneumonia, some heart diseases, or in certain cases of alteration of the blood, as 



Fig. 135. 

 A, Brondgeest's tambour for registering the respiratory movements, b, c, inner and outer 

 caoutchouc membranes ; a. the capsule ; d, d, cords for fastening the instrument to the 

 chest ; S, tube to the recording tambour. B, normal respiratory curve obtained on a 

 vibrating plate (each vibration = "01613 sec). 



in anaemia ; and diminished where there is pressure on the respiratory centre in the medulla, 

 in coma. It is important to note the ratio of pulse-beats to respirations.] 



110. TIME OCCUPIED BY THE RESPIRATORY MOVEMENTS. The 



time occupied in the various phases of a respiration can only be accurately ascer- 

 tained by obtaining a curve or pneumatogram of the respiratory movements by 

 means of recording apparatus. 



Methods. The graphic method can be employed in three directions: (1) To 

 record the movements of individual parts of the chest-wall. 



(1) Vierordt and C. Ludwig transferred the movements of a part of the chest-wall to a lever 

 which inscribed its movements upon a revolving cylinder. Riegel (1873) constructed a 

 " double stethograph " on the same principle. This instrument is so arranged that one arm 

 of the lever may be applied in connection with the healthy side of a person's chest, and the 



