434 Carbon Dioxide Output during Decerebrate Rigidity. 
When the rigidity was abolished by curare the carbon dioxide output 
amounted to 100°8 per cent. (four experiments). 
Controls—As a guarantee of the correct working of the method during the 
two hours following decerebration, it may be stated that during a second 
period with the same decerebrate preparation the carbon dioxide output was 
94°3 per cent. of the first period (two experiments). 
Although precautions were taken to maintain a constant body temperature ; 
it varied a little during some of the experiments. If the “ temperature 
coefficient ” of carbon dioxide output be taken as lying between 2 and 3 
for each rise of 10° C., the fall of temperature practically accounts for 
the diminution of carbon dioxide output in the control and splanchnic, but 
not in the decapitate experiments. In two of the curare experiments the 
internal temperature rose, and the carbon dioxide output also went up, thus 
the average shows no difference from the non-curarised condition. 
These experiments indicate: (1) That the abolition of decerebrate rigidity. 
by curare does not lower the carbon dioxide output, and hence the postural 
tonus requires very little expenditure of energy. Parnas* has recently 
shown that maintained contraction of the adductor muscles of certain 
bivalves requires much less energy than the holding up of the same weight’ 
by vertebrate skeletal muscle. 
(2) That decapitation causes a marked fall in carbon dioxide output, which: 
is not due to the abolition of tonus or fall of blood-pressure. 
* “Arch. f. d. ges. Physiol.,’ 1910, vol. 134, p. 441. 
