ROLLER : RESPIRATORY RESPONSES IN GRASSHOPPERS. 



217 



exposed to the pressure suddenly displayed spasmodic move- 

 ments of all the appendages ; one spasm followed the other 

 in rapid succession. The normal and decapitated did not 

 have spasms, but their respiratory movements were abnor- 

 mally rapid. They were immediately replaced under 275 

 pounds pressure and kept there for about twenty-four hours 

 longer. When observed at the end of that time it was no- 

 ticed that the respiration stopped, and did not return in fresh 

 air and atmospheric pressure. 



While the grasshoppers were under the pressure they did 

 not have spasms ; they appeared when the animals were very 

 gradually removed from the pressure. It was also noticed 

 that the first effect of the high pressure was an acceleration 

 of the respiratory movements and then the rhythm decreased 

 very much in force and rate. 



In another related series of experiments, immature Feb- 

 ruary forms appeared lifeless at the end of twenty-four hours' 

 exposure to 275 pounds pressure, and when removed to at- 

 mospheric air fluid escaped from their mouths, while the ab- 

 domens in the normal animals became greatly inflated, then 

 gradually assumed their normal dimensions again. During 

 an exposure of two hours to atmospheric pressure the heart 

 and respiratory movements reappeared. The animals were 

 again subjected to 275 pounds tension for about thirty hours, 

 when respiration had ceased and was not again established 

 under atmospheric pressure. November and December forms 

 die in less than two days under a pressure of 275 pounds. 



Table IV shows the effect of sudden high pressure on nor- 

 mal and deviscerated mature grasshoppers. 



Table IV. 



