452 PHYSIOLOGY CHAP. 



muscles upon the controlling bulbar centre appears, however, in 

 the i'act that permanent respiratory hemiplegia ensues on unilateral 

 section of the upper cervical cord (Fig. 208). Schiff rightly 

 directed attention to this fact in his last work on the respiratory 

 centre (1894), in order to refute the old doctrine of Brown - 

 Sequard as tentatively revived by Langendorff and Wertheirner. 



It is, however, still uncertain whether we should, with 

 Langendorff, admit the existence of another autonomous inhibitory 

 centre for respiratory movements, along with the controlling 

 centre in the bulb. Landergreen's studies on the circulatory and 

 respiratory phenomena in asphyxia (1897), those of Prevost and 

 Stern on the final respirations (1906), and, lastly, those of Mosso 

 on the asphyxial pause, contain no conclusive arguments for or 

 against the theory of an inhibitory, respiratory, bulbar centre. 



Patrizi and Franchiui, on the ground of certain peculiarities of 



Fio. 208. Pneumograms of most convex part of right (Ts) and left (Td) half of thorax in young 

 hound, operated on three weeks previously by hemisection of cord at level of highest cervical 

 tract. (M. Schiff.) The slight respiratory movements of the right half of the thorax are 

 passive, i.e., they depend on the aspiration of the mediastinum to the left due to elevation of 

 sternum. 



respiratory arrest from centripetal excitation of the vagus (1906-7), 

 are inclined to admit Langendorffs contention. The question is a 

 difficult and complex one, and will require extensive experimental 

 researches before we can hope for its solution. 



IV. It is doubtful whether the bulbar respiratory centre, and 

 the spinal respiratory centres scattered along the cervico-dorsal 

 tract of the spinal cord, really represent the whole of the central 

 nervous mechanisms which take an active part in bringing about 

 the mechanical processes of respiration. In all probability, we 

 must, in addition to the bulbar and spinal centres, also admit the 

 existence of true respiratory centres in the brain. 



We know that the respiratory mechanism can be modified in a 

 variety of ways, both by voluntary impulses and by simple 

 psychical emotions. A practised singer has such perfect control 

 over his own respiratory movements that in expelling the air from 

 his lungs he is able to produce the finest shades of tone during 

 expiration. Again in conversation, and still more in oratory, the 



