26 



ELIZABETH LOCKWOOD THOMPSON 



TABLE l\— {Continued) 



Snail No. 5 — {Continued) 



No. for No. of No. of Duration 



No. of "pressure" trials reactions of 



days stimulus for per response 



tested series day response in sec. 



32 11 1 1 1 

 12 2 1 1 



13-20 3-10 



Totals 10 ■ 2 



Av. per response 1.0 



33 21-30 1-10 



34 31-40 1-10 



Total number of trials (last 20 trials omitted) 20 



Total number of stimuli followed by response 9 



Per cent of stimuli followed by response 45% 



Total number of reactions 36 



Average number of reactions per trial 1.8 



Average number of reactions in only those trials in which response 



occurred 4 



Total time of reactions in seconds 43 



Average time per reaction in seconds 1 . 19 



Average number of reactions per minute (estimated) 50.42 



Summary Snails 4 and 5. 



Total number of stimuli (trials) 37 



Total number of stimuli followed by response 17 



Per cent of stimuli followed by response 45 . 9% 



Table IV shows that when the secondary stimulus, pressure, 

 alone was applied to the inputh of Physa, the mouth reacted in 

 17 out of v37 trials with two individuals, or in 45.9% of the trials. 

 No mucous stimulation was observed. The average number 

 of reactions per response was for Snail 4, 1.25 and for Snail 5, 

 4.0 (Table IV). Snails Nos. 6, 7, 8, 14 were given a similar series 

 of tests which are not here tabulated in detail but are summarized 

 in Table V-C. These showed the follow^ing average number of 

 reactions per response 4.92, 6.09, 8.0, 3.8. The mean for the 

 six snails is 4.67. The mean for the normal food series is for 

 six snails 5.86. For the food-pressure series it is 3.18. The 

 average duration of reactions for the pressure response of trained 

 snails is less than for the normal food response. The average 

 rate per minute is 53.9, 7.65 reactions per minute in excess of 

 that of the normal food response. 



These trials followed 48 hours after the completion of the 



