202 



Mr. J. M. O'Connor. 



Having found (16) that, in the cat anaesthetised with urethane, the physical 

 heat regulation was in part under the control of the skin temperature, I 

 have endeavoured to find if. under similar conditions, the existence of the 

 mechanism suggested by Liebermeister could be experimentally demonstrated. 



The animal, cat or rabbit, was anaesthetised with l|-2 grm. per 

 kilogramme urethane, and, as a routine, a thermometer or thermocouple 

 introduced deep into the rectum, and two others pushed under the skin at 

 either side. A tracheal cannula was inserted, the thorax opened, and the 

 cannula connected up with an apparatus for artificial respiration, permitting 

 measurement of the 2 consumption in short periods after the fashion of 

 Begnault and Eeiset. 



This apparatus (fig. 1) consisted of a mercury pump A, driving and 

 sucking air round in a circuit of rubber tubing under the control of 

 mercury valves, so that, on the down stroke of the pump, the air, having 

 passed through the first valve B, distended the lungs directly connected 

 with the circuit by the tracheal cannula at C, and then forced its way 

 through a wash bottle D, filled with strong potash solution, where the excreted 

 carbon dioxide was absorbed. Beyond this and before the second valve L 

 the circuit communicated through a two-way tap with either of two 

 graduated gas burettes (200 c.c), F and G, counterpoised by the arrange- 

 ment H over acidulated water. A small trap M was introduced between the 

 trachea and the circuit to catch any secreted mucus or condensed water, and 

 by means of two tubes and P across the circuit, furnished with simple 

 taps, the valves could be thrown out of action, equalising the gas pressure 

 throughout the apparatus. 



Observations were started as follows : Oxygen was run through the 

 apparatus, and the two-way tap E turned so that one burette was in 

 communication with the air circuit, the tracheal cannula of the animal, 

 on which the preliminary operations had been performed, connected up with 

 the apparatus, and the motor driving the pump put in action. The second 

 burette was filled with O2 from the gasometer and the quantity read off. 

 After a few minutes the pump was held at the top of its stroke by an 

 assistant, and a stop-watch started. The taps on the bye-passes and P 

 were opened, throwing all the valves out of action, the burette in connection 

 with the circuit drawn up so as to cause complete collapse of the lungs, and 

 then brought back so that atmospheric pressure prevailed within the 

 apparatus. The two-way tap was turned to bring the other burette into 

 connection, the bye-passes closed, and pump restarted. The whole occupied 

 about 10 seconds, and, normally, did not produce the slightest sign of 

 asphyxia. When the burette was nearly exhausted, the other having been 



