128 ILLINOIS ACADEMY OF SCIENCE 



to avoid the appearance of nystagmus when it came as a 

 small relapse. For example, a subject may have been ac- 

 customed to six turnings and have been ready to pass to 

 seven save that organic distress (which, as we have found 

 in other experiments, tends to increase the intensity and 

 duration of the nystagmus) made it impossible for the 

 subject to stand more than four or five turnings without 

 nystagmus. In such cases, and they were too few to ser- 

 iously affect the experiment, the subject was continued 

 at the old number of turnings until he was physiologi- 

 cally stable again. 



We shall now discuss the results. By inspecting Table 

 II, it will be seen that, at the time the investigation was 

 discontinued, subjects C and F could be rotated ten times 



TABLE II 



Giving the nur her of rotation-periods of ten trials (each trial con- 

 sisting of the designated number of revolutions) necessary to enable 

 the several subjects to pass to the next higher number of revolutions 

 per trial without the appearance of nystagmus. That is to say, Subj. 

 A, for example, was given 1 rotation-period of ten trials, each trial con- 

 sisting of one revolution. He then spent 4 rotation-periods where each 

 of the trials consisted of two revolutions and so on. 



No. of Subjects 



in twenty seconds without a perceptible quiver of the eye. 

 Subject A Avas discontinued at nine turns per trial, sub- 

 jects B and T) at seven turns and subject E at six. There 

 is no reason to suppose, however, that these subjects 

 would not ultimately have given the same results as sub- 

 jects C and F. 



Table III shouts, in terms of the number of single revo- 

 lutions, the general course of the increasing inhibition 

 against nystagmus. The fact is revealed that the effect 

 of practice is greater at the beginning of a series than at 



