Section V, 1919 [85] Trans. R.S.C. 



Studies on the Respiratory Centre 



I. The Behaviour of the Respirations After Decerebration 



IN THE Cat 



By J. J. R. MACLEOD, M.B., F.R.S.C. 



(Read May Meeting, 1919.) 



Our knowledge of the functions of the respiratory centre depends 

 on observations which have been made either on anaesthetised labora- 

 tory animals or on man in the normal state. To both groups of re- 

 searches serious objections can be raised; to the former because of 

 the use of anaesthesia, which is well known greatly to depress the 

 excitability of the respiratory centre, and to the latter because of the 

 limited variety of observations which it is practicable to make. As a 

 first step to a further investigation of the respiratory function, there- 

 fore, it became necessary to seek for some method applicable to 

 laboratory animals, in which the activities of the centre would not be 

 dulled by the use of anaesthetics. It has been found that this require- 

 ment can be satisfactorily met by using the decerebrate preparation 

 which was originally described by C. S. Sherrington,^ and subsequent- 

 ly more closely studied by Theile,- Sherrington,^ Forbes and Sher- 

 rington,* Miller and Sherrington^, Weed^ and Cobb, Bailey and Holtz^. 



The section of the brain stem is usually made about the level of 

 the anterior corpora quadrigemina. After the effects of the initial 

 anaesthesia have passed off a state of rigidity (plastic tonus) of the 

 postural musculature supervenes and the breathing usually remains 

 more or less normal. 



In using the decerebrate preparation for investigation of the re- 

 spiratory function one must not lose sight of the fact that important 

 controlling influences have been removed from the centre, namely 

 those derived from the higher cerebral centres, and that the respiratory 

 function under these conditions may be as far removed from the 



1 Sherrington, C. S. Journ. Physiol., 1897, XXII, 319. 



2 Theile, F. H. Journ.. Physiol., 1904, XXXII, 358. 



3 Sherrington, C. S. Quart. Journ. Physiol., 1908, II, 109. 



* Forbes, A, and Sherrington, C. S. Am. Journ. Physiol., 1915, XXXV, 327. 



6 Miller, F. R., and Sherrington, C. S. Quart. Journ. Physiol., 1915, IX, 147. 



«Weed, L. H. Journ. Physiol., 1914, XLVIII, 205 and Am. Journ. Physiol., 

 1917, XLIII, 131. 



' Cobb, S., Bailey, A. A., and Holtz, P. R. Am. Journ. Physiol., 1917, XLIV, 

 239. 



