290 



A MANUAL OF PHYSIOLOGY 



the obliquely-cut ends of the metal cylinder D. The tube G is con- 

 nected with a tambour or with a bellows recorder (Fig. 131). 



4. The Effect of Temperature on the Respiratory Centre Heat 



Dyspnoea. Set up an arrangement 

 for taking a respiratory tracing as 

 in 2 (footnote, p. 288). Anaesthetize 

 a dog, and fasten it, back 

 downward, on a holder. 

 Make an incision in the 

 middle line of the neck, 

 commencing a little below the cri- 

 coid cartilage, and extending down 

 for 4 or 5 inches. Insert a cannula 

 into the trachea. Isolate both caro- 

 tid arteries for as great a distance as 

 possible, and arrange them on the 

 brass tubes shown in Fig. 132. Con- 

 nect two adjacent ends of the tubes 

 by a short rubber tube. Connect one 

 of the remaining ends to a funnel, 

 supported on a stand, and the other 

 to a rubber tube hanging over the 

 table above a large jar. Slip two or 

 three folds of paper between the 

 tubes and the vagus nerves. Heat 

 two or three litres of water to about 



6s C. (a] Now connect the tracheal 

 light wooden base and top, to whicn J , v ,> j_v 



is cemented very flexible (organ key) cannula with the tambour. As soon 

 leather, properly creased for expan- as the tracing is under way, let the 

 sion and con traction ;C, writing lever, hot water run through the funnel 



and tubes into the jar. Mark on 



the tracing the point at which the flow of the hot water was 

 begun, and go on passing it until it has produced an effect. Then 

 stop the drum, and circulate water at the ordinary temperature 



till the breathing is again 

 normal. Then, while a 

 tracing is being taken, 

 pass ice-cold water 

 through the tubes, and 

 again notice the effect. 



(b) Expose the sciatic. 

 Pass ice-water through 

 the tubes, and while a 

 respiratory tracing is 

 A, cylindrical portion of tube ; B, flattened being taken stimulate 

 portion in the groove between which and A, the its central end with in- 

 artery, lies ; C, cross-section, showing the lumen 



FIG. 131. BELLOWS RECORDER 



(CRILE). 

 B, a lead tube connected with the 



FIG. 132. ARRANGEMENT FOR HEATING OR COOL- 



ING THE BLOOD IN THE CAROTID ARTERIES. 



duction shocks so weak 

 as just to cause an effect. 

 Pass water at air tem- 

 perature through the 

 tubes, and repeat the 

 stimulation with the 

 coils at the same dis- 

 tance. Do the same 

 while hot water is being 

 passed through the tubes, and compare the results. Always allow 

 the water to pass for a time before making an observation. 



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 a 

 funnel containing hot or cold water or with the 

 outflow tube, as the case may be. 



