192 
IOWA ACADEMY OF SCIENCE Voi.. XXVIII, 1921 
PEATE VI 
13, 14, 15, 16 and 17. Series of responses of frog esophagus when 
treated with 12.25, 9.00, 6.25, 3.12, 1.56 vols. per cent ethyl alcohol res- 
pectively. On comparison of relative heights from that of the normal 
in each case an index as to relative toxicity or sensitization in the series 
can be had. The forms of the resulting curves also show in the relax- 
ation phase a graded change from a maintained plateau in the first to a 
nearly normal decline in the last. 
18, 19, 20, 21, 22 and 27. Typical series of responses of earthworm 
muscles in regions of worm 57, showing gradations in height and form 
when subjected to various concentrations of ethyl alcohol. These re- 
cords show unmistakably that the higher concentrations are markedly 
toxic, and that the weaker ones are decidedly sensitizing. 
23. Fatigue responses in earthworm muscle under constant interval of 
stimulation, finally rejuvenated by treating with 0.25 vol. per cent ethyl 
alcohol. 
