author's abstract of this paper issued 

 by the bibliographic service, december 27 



THE EFFECT OF LIGHT AND DECAPITATION ON THE 

 RATE OF CO2 OUTPUT OF CERTAIN ORTHOPTERA 



JOSEPH HALL BODINE 



Zoological Laboratory, University of Pennsylvania 



THREE FIGURES 



As a result of the work of A^arioiis investigators, particularly of 

 Moleschott/ J. Loeb,- and C. Ewald,^ it has been pointed out that 

 the effects of light on the respiratory exchange of organisms are 

 rather variable. In some cases definite increases in the respira- 

 tory exchange have been noted, while in others no direct effects 

 have been detected. More recent investigations, especially those 

 of Holmes,^ Garrey,^ and J. Loeb,*^ on the tropic responses of 

 organisms to light, have definitely shown that the primarj^ effect 

 of light consists in changes in the tension or tonus of muscles. 

 It is the intention of this paper to show that such changes in 

 muscle tension or tonus in an insect are associated with corre- 

 sponding detectable changes, in the rate of carbon-dioxide output 

 of the organism. 



The choice of suitable material and a method delicate enough 

 to detect slight differences in COo output are of prime importance 

 in such an investigation. Grasshoppers have been chosen because 

 of the ease in handling, their relatively small size, the fact that 

 ,they show rather definite tropic responses, and, lastly, that by 

 proper handling their body movements can be practically elimi- 

 nated during experiments. Nymphs or adults of the following- 

 species of grasshoppers were used: Chortophaga australior, 

 Chortophaga viridifasciata, Melanoplus differentialis, andDichro- 

 morpha viridis. All animals were kept in the laboratory and 

 fed grass, lettuce, etc. — the same as those used for other experi- 

 mental work. Carbon-dioxide determinations were made bj' 

 the indicator method described by Dr. N. H. Jacobs, '^ of this 



47 



