PRACTICAL EXERCISES 



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FIG. 100. ARRANGEMENT FOR RESPIRATORY TRACINO. 



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 mu>t 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. 



FIG. i oo<3. ARRANGEMENT FOR HEATING OR COOLING THE BLOOD IN 

 THE CAROTID ARTERIES. 



A, cylindrical portion of tube ; B, flattened portion in the groove between which and 

 A the artery lies; C, cross-section, showing the lumen extending into B; D, rubber 

 tube attached to a brass tube soldered into A. The other end of A has a similar 

 brass tube soldered into it (not shown in the figure). This is connected by a rubber 

 tube with a similar apparatus, on which the other carotid lies. D is connected with & 

 funnel cont3iing hot or co'.d water or with the outflow tube, as the case may be. 



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