2IO 



JOSEPHINE ALBERTA WILLIS. 



In order to prevent confusion of connotation of the words used 

 in describing the endpoints in the experiments the two following 

 terms are defined: 



1. First movement designates the first reflex, i.e., crawling or 

 stirring of the animal after it has been removed from the influence 

 of the gas. 



2. Recovery indicates that the animal has returned to a 

 normal state. 



EXPERIMENTS. 



I. Effects of Pure Carbon Dioxide. 



The animals used in these experiments, Melanoplus differentialis 

 and Melanoplus femur rubrum, were raised entirely under 

 laboratory conditions. 



TABLE I. 



SHOWING VARIATION IN TIME TO FIRST MOVEMENT AFTER SHORT EXPOSURES TO 



PURE CARBON DIOXIDE. 



Adults and nymphs of both sexes were placed separately in 

 airtight tubes connected with a Kipp generator. The carbon 

 dioxide was made by the action of hydrochloric acid on calcium 

 carbonate, passed through concentrated sulphuric acid, pyrogallol 

 and distilled water, thence into tubes containing the animals, and 



