288 A MANUAL OF PHYSIOLOGY 



2.* Production of Apnoea and Periodic Breathing in Man. Arrange 

 for taking tracings of the respiratory movements from a fellow- 

 student as in i. Let the subject of the experiment recline in a per- 

 fectly easy position in an armchair. Let him then breathe deeply 

 and frequently for about two minutes, so as to produce a prolonged 

 apncea of about two minutes' duration. Whenever any desire to 

 breathe returns, the breathing is to be allowed to take its own course. 

 It may be expected at first to be of the periodic (Cheyne-Stokes) type. 



3. Tracing of the Respiratory Movements in Animals. (a) Set 

 up the arrangement shown in Fig. 129, and test whether it is air- 



FIG. 129. ARRANGEMENT FOR RESPIRATORY TRACING. 



Two glass tubes are inserted through a cork in the mouth of the large bottle. 

 One of them has a small piece of indiarubber tubing on it, which is closed or 

 opened, as may be required, by a screw-clamp. The other is connected by a 

 rubber tube with a recording tambour. The tubulure at the bottom of the bottle 

 is closed by a cork, through which passes a glass tube, connected by a rubber 

 tube with the tracheal cannula. If no bottle with tubulure is available, it is only 

 necessary to pass through the cork, down to the bottom of the bottle, a third 

 glass tube, which is connected with the tracheal cannula. While a tracing is being 

 taken the animal breathes the air contained in the bottle. When this becomes 

 vitiated the respiratory movements are exaggerated and a normal tracing is no 

 longer obtained. For this reason the tracheal cannula must be connected with the 

 bottle only at the moment when a tracing is to be taken. The arrangement is 

 most suitable for a small animal. 



tight. Have also in readiness an induction machine and electrodes 

 arranged for an interrupted current. Anaesthetize a rabbit with 

 chloral or ether (p. 204), or a small dogf with morphine and ether, 



* This experiment is only to be attempted under the direct supervision 

 of the demonstrator. 



f If a large dog is used the bottle should be omitted, the tracheal cannula 

 being connected with the stern of a T-tube. One end of the horizontal limb 

 of the T-tube is connected with the tambour; the other is provided with a 

 rubber tube, which can be partially closed by a screw-clamp to regulate the 

 excursion. Ether may be given when required by connecting the horizontal 

 limb of the T-tube with a bottle with two glass tubes in the cork (p. 186). 



