AN ASS 
Carbon Dioxide Output during Decerebrate Rigidity. 
(Preliminary Communication.) 
By H. E. Roar, D.Sc. Liverpool, M.D. Toronto. 
(Communicated by Prof. C. S. Sherrington, F.R.S. Received December 28, 1910, 
—Read March 2, 1911.) 
(From the Physiological Laboratory, University of Liverpool.) 
These experiments were undertaken, at suggestion of Prof. Sherrington, 
to attempt a determination of the amount of energy necessary for maintaining 
tonus in skeletal muscle. 
The carbon dioxide output has been measured in decerebrate cats, and its 
amount compared with the amount given off by the same animal after 
procedures that abolish the tonus of the decerebrate preparation. These 
procedures have consisted of decapitation and intravenous injection of curare. 
The pulmonary ventilation was uniform throughout, as artificial respiration 
was carried out by means of a pump. 
The animals were anesthetised and decerebrated. They were kept ina 
chamber, the air of which was moist and approximately at body temperature. 
The ingoing air was freed from carbon dioxide, moistened and warmed. The 
outgoing air was dried, and the carbon dioxide was absorbed by soda lime 
and weighed. The period of experiment was divided into two halves of 
two hours’ duration each. At the end of the first half the observations were 
interrupted for just so long as was necessary for the procedures required for 
the second half. 
‘The results are expressed as a ratio, namely, the average percentage that 
the carbon dioxide output of the second half forms of the first. | 
Decapitation lowered the carbon dioxide output to 66°9 per cent. (four 
experiments), the output in the previous two hours with the decerebrate 
preparation being considered as 100. The diminished output is mainly due 
to lowered metabolism of skeletal muscle, because in an experiment in which 
the cat had been eviscerated previous to the respiration experiment the 
second half gave a result 61:1 per cent. of the first. 
It was thought possible that the diminished output after decapitation 
might be due to lowered blood-pressure, and cutting the splanchnic nerves 
on both sides did reduce the output to 90°7 per cent. (two experiments). 
The greater reduction in the decapitate experiments cannot be due to 
hemorrhage, as practically no blood was lost by decapitation. 
