282 M. E. Baudelot on the Respiration of Insects. 
' [In a second experiment, at 2 0’clock p.m., I made a ligature a 
little behind the metathorax, and effected the section of the body 
immediately in front of this. In this way I was quite sure that 
I had removed the metathoracic ganglion, which is situated at 
the centre of the space between the insertions of the second and 
third pairs of legs. At 4 o’clock, however, the number of re- 
spirations was eighteen per minute, and the respiration only pre- 
sented a few irregularities ; at 3 o’clock p.m. next day it was still 
possible to perceive some respiratory movements. To leave no 
chance of uncertainty, I dissected the portion of the body which 
I had cut away in front of the ligature: it contained the three 
thoracic ganglia as well as the first abdominal one. 
In a third experiment, the ligature and section were made at 
the fifth segment of the abdomen, when the respiratory move- 
ments, although much weakened and rendered irregular, still 
persisted for more than twenty-four hours. Nevertheless the 
portion of the body anterior to the section contained the whole 
of that part of the nervous chain that extends from the head to 
the fifth abdominal ganglion. 
From these two latter experiments it is quite evident that the 
metathoracic ganglion is not the prime motory focus of the 
respiratory movements, since, after the complete removal of this 
ganglion, respiration continued to be effected for a period of 
twenty-four hours. With regard to the subcesophageal ganglion, 
I have been unable to discover in it any special coordinative 
property ; and when the respiratory movements were produced 
independently of its influence, I always saw the five appendages 
of the last abdominal segment concurring normally, as before, 
in the respiratory act with the whole of the other segments of 
the abdomen. 
I repeated these experiments upon the adult Libellula with 
equally conclusive results. The complete section of the body 
behind the metathoracic ganglion does not cause the suspension 
of the respiratory movements in the portion posterior to the 
section, any more than in the larva. Thus in one case, in which 
I made a ligature and then a section behind the second segment 
of the abdomen, the respiratory movements persisted for eight 
hours; the inhalations, which were very regular, rose to fifty 
per minute, and yet the metathoracic ganglion had been cut 
away with the anterior portion. In another experiment, the 
respiration lasted seven hours; it was very regular, and the 
number of inhalations was sixty-five per minute. 
Lastly, in a final experiment, I cut a piece out of the abdomen 
including only three segments (4-6); and in this I observed 
very appreciable movements of respiration for some time. 
These results and others of precisely similar nature, which I 
