TIME OCCUPIED BY THE RESPIRATORY MOVEMENTS. 



169 



other on the diseased side. In the case of animals placed on their backs, Snellon introduced 

 a long needle vertically through the abdominal walls into the liver. Rosenthal opened the 

 abdomen and applied a lever to the under surface of the diaphragm, and thus registered its 

 movements (Phrenograph). 



(2) An air-tambour, such as is used in Brondgeest's pansphygmograph (fig. 135, A), may be 

 employed. It consists of a brass vessel, , shaped like a small saucer. The mouth of the brass 

 vessel is covered with a double layer of caoutchouc membrane, b, c, and air is forced in between 

 the two layers until the external membrane bulges outwards. This is placed on the chest, and 

 the apparatus is fixed in position by means of the bands, d, d. The cavity of the tambour 

 communicates by means of a caoutchouc tube, s, with a recording tambour, which inscribes its 

 movements upon a revolving cylinder. Every dilatation of the chest compresses the membrane, 

 and thus the air within the tambour is also compressed. [A somewhat similar apparatus is 

 used by Burdon-Sanderson, and called a " recording-stethograph. " By it movements of the 

 corresponding points on opposite sides of the chest can be investigated.] A cannula or 

 oesophageal sound may be introduced into that portion of the oesophagus which lies in the 

 chest, and a connection established with' Marey's tambour {Rosenthal). [This method also 

 enables one to measure the intrathoracic pressure.] 



Marey's Stethograph or Pneumograph. [There are two forms of this instrument, one modi- 

 fied by P. Bert and the more modern form (fig. 136). A tambour (h) is fixed at right angles to a 

 thin elastic plate of steel (/). The , 



aluminium disc on the caoutchouc 

 of the tambour is attached to an 

 upright (J), whose end lies in con- 

 tact with a horizontal screw (g). 

 Two arms (d, c) are attached to 

 opposite sides of the steel plate, 

 and to them the belt (e) which 

 fastens the instrument to the 

 chest is attached. When the 

 chest expands, these two arms are 

 pulled asunder, the steel plate is 

 bent, and the tambour is affected, 

 and any movement of the tam- 

 bour is transmitted to a register- 

 ing tambour by the air in the 

 tube (a)]. 



(2) To record variation in 

 volume of the thorax or of the 

 respired gases. 



For this purpose E. Hering 

 secures the animal, and places it 

 in a tight box provided with two openings in its side ; one hole contains a tube, which is 

 connected to a cannula tied into the transversely divided trachea of the animal, so that 

 respiration can go on undisturbed. In the other orifice is fixed a water-manometer provided 

 with a swimmer arranged to write on a recording surface. Gad registered graphically the 

 respired air by means of a special apparatus ; the expired air raised a very light and carefully 

 equipoised box placed over water. As it was raised, it moved a writing-style. During inspira- 

 tion the box sank. 



(3) To record the rate at which the respiratory gases are exchanged. 



If the trachea of an animal, or the mouth of a man (the nostrils being closed), be connected 

 with a tube like that of the dromograph (fig. 113), then during inspiration and expiration the 

 pendulum will be moved to and fro by the air, and the movements of the pendulum can be 

 registered. [Some years ago, an instrument, called the " Anapnograph," was constructed on 

 this principle.] 



The curve (fig. 135, B) was obtained by placing the tambour of a Brondgeest's 

 pansphygmograph upon the xiphoid process, and recording the movement upon a 

 plate attached to a vibrating tuning-fork. The inspiration (ascending limb) begins 

 with moderate rapidity, is accelerated in the middle, and towards the end again 

 becomes slower. The expiration also begins with moderate rapidity, is then 

 accelerated, and becomes much slower at the latter part, so that the curve falls 

 very gradually. 



Inspiration is slightly shorter than Expiration. According to Sibson, the 



Fig. 136. 

 Marey's stethograph. 



