xni KESPIKATOEY EHYTHM 447 



nceud vital of Flourens) constitutes the bulbar centre of respira- 

 tion. Evidence for this theory is given, according to Gad, in the 

 fact that very circumscribed electrical excitation by means of fine 

 needles, varnished as far as the points, and thrust into the parts of 

 the formatio reticularis which lie above and beneath those parts 

 whose destruction produces respiratory arrest, provokes only an 

 acceleration of respiratory rhythm, and not a tetanus of the 

 inspiratory muscles, as occurs when the respiratory tracts in the 

 lateral bundles of the cervical cord are excited. 



Whatever the extension of the true bulbar respiratory centre, 

 it is certain that the symmetry of the respiratory movements on 

 the two sides of the thorax depends on the intrabulbar commissural 

 fibres, which unite the two lateral halves of the respiratory 

 centre ; and that the descending paths, which unite the bulbar 

 centre with the spinal centres of the respiratory muscles, and run 

 directly, without decussating, in the lateral bundles and in the 

 highest portion of the cervical region, are probably located in the 

 processus reticularis, which lies between the anterior and posterior 

 horns of the grey matter of the cord. 



III. We have already seen that Brown-Sequard, in 1858, 

 denied the existence of a bulbar respiratory centre, and interpreted 

 the results of Flourens' experiments as inhibitory phenomena, by 

 which the rhythmic activity of the spinal centres, the sole cause 

 of the respiratory movements, were suspended. The successful 

 destruction of the so-called nceud vital without abolishing respira- I 

 tion seemed to justify his opinion. Now, however, we know that I 

 the noeud vital does not constitute the whole of the bulbar ; 

 respiratory centre, which is much more extensive, and apparently 1 

 comprises the entire formatio reticularis. / 



In 1880 Langendorff attempted to resuscitate the doctrine of 

 Brown-Sequard, in Germany, on the strength of an interesting fact 

 discovered in 1874 by P. Eokitansky. He saw that in young 

 rabbits it is possible for a certain time to revive the respiratory 

 movements suppressed by separation of the bulb from the 

 spinal cord, after suspending artificial respiration and slightly 

 strychninising the animal, to increase the excitability of the cord. 

 Schroff confirmed this in 1875, adding that in order to reinstate 

 some respiratory movements in animals with divided bulb, without 

 employing strychnine, it was only necessary to avoid cooling 

 during artificial respiration by keeping the animal in a warm 

 chamber. Langendorff (1880)- further found, after dividing the 

 bulb, that natural respiration was reinstated for a considerable 

 time in newborn puppies and kittens without resorting to 

 adventitious aids other than artificial respiration. Since it is 

 well known that in the newborn, as in the lower animals, the 

 functions of the spinal cord exhibit a far greater degree of 

 autonomy and independence of the higher centres than in the 



