1 I FECTS OF CARBON DIOXIDK. 



fluid. Consequently with an excess of carbon dioxide it is quite 

 probable that much of it is absorbed by the tissue cells. Jacobs 

 (3) has demonstrated the easy permeability of the cell membranes 

 to carbon dioxide and in studying the effect of carbon dioxide on 

 prof op]a:>mii \ i-< . .-ity of Paramecia and of .-1 ; -. lie found 



that -horter -\pi .-u res to the gas cause a great decrease in 

 viscosity \\hile longer ones cause an incr- :il within limits 



I. Mih an- n-\er.-ible (4). Hence changing vi-co-ity of the pn.to- 

 pla-m .f the _ i M hopper musde cell attended by liquefaction or 

 produce the limpness or stillne-- of the animal. 



There nia\ also be a chemical explanation of the effect- of the 

 n the animals. Carbon dioxide, by goiny; into -olution in 

 the blooil iin n-a-ing the hydrogen ion concentration. or ly acting 

 in an midis- o( i.ited state, may stimulate the ncr\ e ^anijia in the 

 alxloinin.il -cements causing breathing m.>\cment-. tlni- : 

 dm in- an effect similar to that caused by -tinmlation of the 

 'iraioj-y center in mammals as demonstrated l>y Hooker, 

 \\ il-on and Connett (5) and by Scott (6). 



Another theory is suggested by the work of Kidd 7 \\ herein 

 he attributes the resting stage in moist seed- to ,1 nan -otic a< tion 

 of carbon dioxide. 1 Vrhaps this idea m.i\ b< correlated \\ith 

 < i Main data on insects. Buddenbrock and Kohr ^ uoikin^ 

 \\ith the \\alkin.; stick, Dixippus morosns, found that the rate of 

 tiling movements is affected by the carbon <lio\i<le content of 

 tin- air. \\'ith increasing concentrations from <> to i per cent, the 

 rate oi bit.ithing suddenly increases, thi- i- folloudl b 

 di Hi :in at 10 to 15 per cent, then i- inal ii 



at _?5 to ^o per cent, a decrease follows and a; vs t r rent. 



n--piratoi\ nio\ements cease. In the pri--ent paper there \\as 

 found to be little or no change in the carbon dioxide content of an 

 enclo-rd -p. ice containing an animal, when the original content 

 \\a- from 75 to loo per cent, carbon dioxide. Thi- excess carbon 

 dioxide undoubtedly produces a deep narcosis in the >pper. 



It max be of interest to note that experiment- have been 

 carried out by the author using a modified Van Slyke (9) method 

 for determining the carbon dioxide content of in-ect blood. It 

 -tcm- that the carbon dioxide content of grasshoppers' blood is 

 Io\\er than that of mammalian blood and i- approximately 30 

 cubic centimeters CO 2 per IOO cubic centimeter- of v. hole blood. 



