597 



I thought that it would be interesting to decide, if, at the 

 time that there is an effort at inspiration, there is not also an influ- 

 ence of the medulla oblongata on the par vagum, more or less 

 similar to that which exists when we galvanize or otherwise irritate 

 the medulla oblongata. To ascertain if it is so, I have made ex- 

 periments on newly-born animals, and on birds. As I have already 

 published some of the results of my researches on newly-born animals, 

 and as these results are not so completely decisive as those of my 

 experiments made on birds, I will merely give here a summary of 

 what I have seen in these last animals. I have found the same 

 facts in ducks, geese and pigeons, but as I have repeated the 

 experiments more frequently on the last-mentioned animals, I will 

 speak of them only. When their abdomen has been widely opened 

 and their heart exposed to sight, pigeons may live, as it is well 

 known, for a long while. I wait until they are almost dying, having 

 only one, two, or three inspirations in a minute, and then, if the 

 weather is cold, and if the animal has lost many degrees of its 

 temperature, I find that, at each effort it makes to inspire, the 

 heart either almost suddenly stops, or beats much less quickly. 



I have frequently seen the heart completely arrested for five or 

 ten seconds, and twice for twenty or twenty-five seconds, in cases 

 where there was only one respiration in two minutes. This stoppage 

 of the heart's movements was the more remarkable, as they were at 

 the rate of more than two hundred in a minute, when the effort at 

 inspiration took place. To decide that it was in consequence of an 

 influence of the par vagum that this occurred, I divided this nerve 

 in the neck, and then found that there was no more influence of the 

 inspiration on the heart, or if there was, it consisted in an augment- 

 ation of the frequency of the movements of this organ an augment- 

 ation due to the shaking of the heart when the chest dilated. 



Sometimes, when the heart was very irritable, and when the efforts 

 at inspiration were still frequent and not energetic (the par vagum 

 being undivided), these efforts were accompanied, or rather imme- 

 diately followed, by an increase in the strength of the heart's move- 

 ments, probably caused by the shaking. But always when the 

 inspiratory efforts were energetic and rare, they co-existed with a 

 diminution or a momentary cessation of the heart's contractions ; 

 and always in these cases the section of the par vagum has destroyed 



