128 LOCALIZED ELECTRIZATION. 



and knows also that the most feeble f\iradization of the superior 

 laryngeal suspends respiration instantly. Should he, therefore, 

 doubt that the medulla has been really excited in the experiments 

 during which a current of the same degree of force has been 

 passed from the mouth to the anus, without producing great 

 disturbance of the respiration ? 



It is necessary, as we have seen, that the current should attain 

 a yery high degree of tension, in order that the respiration should 

 be completely stopped, or that the heart should cease to beat. 



It is not even shown that, under these circumstances, the 

 arrest of the respiration and of the heart is due to excitation of 

 the medulla oblongata. Indeed, the tetanic contraction was not 

 at its maximum, so that the inspiratory muscles, principally the 

 diaphragm and the intercostals, which were only in a certain degree 

 of rioidity, were able, under the influence of a great inspiratory 

 effort, to contract yet more, and to produce movement. In the 

 second experiment it is manifest that the maximum tetanic state 

 of the same inspiratory muscles would be necessarily opposed 

 to any respiratory movement of the thorax ; by Avhich may be 

 explained the rapid death which befel the animals thus treated. 

 The arrest, observed in the last experiments, of the oscillations of 

 a needle thrust into the heart, does not prove that that organ had 

 then ceased to beat ; because the oscillations may have been 

 stopped by the extreme rigidity of the intercostal muscles traversed 

 by the needle, while in the former experiments these muscles 

 were not sufficiently rigid to stop them. The correctness of this 

 explanation is shown by the fact that, when the muscles relaxed 

 on the suspension of the faradization, although the rabbit had 

 ceased to live, small oscillations of the needle again gave evidence 

 of contraction of the heart. 



The facts and considerations that I have advanced show, there- 

 fore that the mode of general faradization under discussion does 

 not powerfully excite the medulla oblongata, and this is all that I 

 endeavour to establish. 



I do not maintain that the procedure exerts no influence upon 

 the medulla oblongata. I do not think, indeed, that in these experi- 

 ments, when one of the rheophores is placed in a region (the 

 mouth) deriving its nerves from the medulla oblongata, and from 

 a part of the pons Varolii, that these points of the nervous cen- 

 tres can possibly altogether escape excitation. Certain facts 

 show, indeed, that there is a real reflex action of the medulla. 



Thus, when the faradization has been moderate, we have seen 

 that the cardiac and respiratory movements have been increased 

 in frequency. Lastly, we may see that, in asphyxia, this mode of 



