Kansas Dnivehsity Science Bulletin. 



Vol. Ill, No. 7. APRIL, 1906. l^o^'^xni,™": 



EESPIRATORY RESPONSES IN THE GRASSHOPPER TO 

 VARIATIONS IN PRESSURE. 



BY L. W. ROLLER. 



From the Physiological Laboratory of the University of Kansas. 



With plate XLI. 



npHE existence of a respiratory center in vertebrates evi- 

 -*- dently gave rise to the idea of a coordinating center of res- 

 piration in insects located in the head. Faivre^ assumed that 

 the subcesophageal ganglion in Dytiscus has a coordinating in- 

 fluence on the respiratory movements, because, when the sub- 

 cesophageal ganglion, or brain, is destroyed, the respiration is 

 not interrupted, whereas, lesion to the subcesophageal ganglion 

 causes cessation of respiratory movements. Hyde ^ found that 

 after the extirpation of the subcesophageal ganglion in Limu- 

 lus respiration ceased, but when the shock effect had passed 

 off respiratory movements gradually began again, and that 

 the abdominal ganglia are centers for the rhythmical respira- 

 tory movements. This fact was also demonstrated by Ewing,' 

 who, while working in this laboratory, observed that the 

 abdomen of the grasshopper may be divided into several 

 parts, each of which executes mechanical respiratory move- 

 ments. These facts prove the erroneousness of Faivre's as- 

 sertions. 



The effects of changes in barometric pressure upon the 

 respiratory movements have been observed upon both lower 

 and higher forms than the grasshopper, none of which, how- 

 ever, had the peculiar properties that make this animal so 



1. Faivre : Comptes rendus de 1' Academic des Sciences, 1860, vol. LI, p. 38. 



2. Hyde, Ida H.: Journal of Morphology, 1894, vol. IX, No. 3, p. 431. 



3. Ewing, H. Z.: Kansas University Science Bulletin, 1904, vol. I, No. 2, p. 306. 



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