118 Messrs. T. L. Brunton and J. Fayrer on the [Jan. 22, 



hardly be due to the division of the vagi in this instance, as that operation 

 is usually followed by paleness of the membrane. The intestinal move- 

 ments are quickened by the poison, since there is purging, which can- 

 not be due to increased intestinal secretion, as the stools consist 

 chiefly of mucus. The movements continue for a considerable time 

 after death. 



Effect of Cobra-poison upon Respiration. 



The action of cobra-poison upon respiration is perhaps the most im- 

 portant of those which it exerts upon the organism ; for it is through this 

 action that death is generally caused. The respiratory movements, besides 

 being frequently altered in form, are generally quickened after the intro- 

 duction of the poison ; then the number sinks to the normal or even below 

 it ; they become weaker and, finally, cease altogether. The blood being 

 no longer aerated, becomes more and more venous, and, by irritating either 

 the respiratory centre itself or some nervous centre closely associated 

 with it, occasions general convulsions. These disappear whenever arti- 

 ficial respiration is begun and the blood again aerated; while they 

 reappear when the respiration is discontinued and the blood regains its 

 venous character. This condition is to be observed in Experiment LXII. 

 The dependence of the convulsions on the venosity of the blood is well 

 shown by Experiment YTTT. -of our former communication, where the con- 

 dition of the blood was indicated by the colour of the fowl's comb, and as 

 this became florid, or livid, the convulsions disappeared or returned. After 

 they have continued a short while the convulsions cease ; for the venous 

 blood does not maintain the vitality of the nervous centres sufficiently to 

 keep them in action ; but if artificial respiration be recommenced, the first 

 effect of aerating the blood is to renew the convulsions, by increasing the 

 vitality of the nervous centres, and rendering them again susceptible to 

 the action of a stimulus, though the convulsions disappear as soon as the 

 arterialization has proceeded sufficiently far. 



Increased rapidity of the respiratory movements may depend either 

 upon greater excitability of the respiratory centre in the medulla, or 

 upon stimulation of some of the afferent nerves which have the power to 

 accelerate it. The chief of these are the pulmonary branches of the vagus, 

 though there are probably others proceeding from the cerebrum, through 

 which the emotions influence the breathing, and others from the general 

 surface of the body. 



In order to ascertain the cause of the acceleration of respiration several 

 experiments were made. Experiment LXIII. shows that it is not due to the 

 action of the poison on the cerebrum ; for it occurs after the cerebral 

 lobes have been removed. The ultimate arrest of respiration is probably 

 due, in part, to paralysis of the medulla, and, in part, to paralysis of the 

 motor nerves distributed to the respiratory muscles. The complete insen- 

 sibility of the phrenic nerve to the strongest stimuli, while the sciatics 



