RHEOTAXIS IN ISOPODA 



331 



TABLE 29 

 Stream isopods from low oxygen in an oxygen gradient 



Experiment 



Control 



current: 



O2 OF 



culture: 



O2 gradient cc. per liter 



response 



gradient 



response 



gradient 



response 



Totals 



Percentage of total 

 trials 



3.07 

 23 



1.82 

 26 

 95 

 80 

 22 

 42 



3.24 

 79 

 17 



384 



29 



5.47 

 18 



43 



26 



9 



38 



12 

 30 



7.63 



40 

 8.14 

 151 

 286 



71 



26 



96 



11.00 



61 



28 



cc. per mm 



600 



400 

 525 

 525 

 300 

 300 



300 

 300 



41 

 189 

 65 

 25 

 39 



67 



77 



6 

 38 

 43 

 19 



86 



11 

 11 



26 



139 

 197 



82 

 22 

 51 



74 

 14 



cc. per liter 



2.44 



2.12 

 2.22 

 2.56 

 3.00 

 2.00 



0. 3 

 2.44 



185 



14 



759 



57 



508 



38 



217 



17 



605 



45 



TABLE 30 



Stream isopods in a carbon dioxide gradient 



From water having less than 2 cc. per liter current 300 cc. per min. 



Experiment 



CO2 gradient CC. per liter 



response 



gradient 



response 



gradient 



response 



gradient 



response 



gradient 



response 



gradient 



response 



Totals 



Per cent of total num- 

 ber of trials 



24 

 25 

 45 

 28 

 59 

 20 

 60 



7 



80 



19 



551 



5 



104 



26 



12 



3.5 

 45 



3 

 40 



3 

 37 



7 



36 

 20 

 59 

 138 

 72 



289 



71 



Control 



30 

 17 

 36 

 23 

 52 

 38 



196 



47 



3 

 29 



8 

 4 

 9 

 6 



59 



14 



44 

 34 

 16 

 15 

 17 

 40 



166 



39 



