152 PSYCHOLOGICAL EFFECTS OF ALCOHOL. 



subjects as a basis for calculation, it would appear that for every 

 5 added to the amplitude of the eye-movement between 5 and 40, 

 about 10 a is added to the duration of the movement. But the 

 apparent implication of a fixed maximum velocity of 10 a for each 5 

 is false. The experiments of Guillery 1 and of Bruckner, 2 as well as 

 Erdmann and Dodge's 3 experiments by the Lamansky method, all 

 showed that the maximum velocity of the eye during movements of 

 large amplitude is greater than the maximum velocity during move- 

 ments of small amplitude. The record of every eye-movement of the 

 first type, between 5 and 40, shows three distinct phases. The first 

 phase consists of a positive acceleration to a maximum velocity. This 

 is maintained for a considerable angle of movement, and constitutes the 

 second phase, giving place in turn to a negative acceleration phase as 

 the eye comes to rest. The relation of these phases is not constant. 

 In the shortest excursions measured, the second phase is very short, while 

 in the longest excursions, with the exception of a peculiar modification 

 in the abductive movements, the second phase is by far the most 

 conspicuous. Moreover, if one superimposes a curve for a movement 

 of 15 on a curve for a movement of 40, the second phase of the latter 

 record will be found to incline slightly more to the horizontal. This 

 confirms the law that the maximum as well as the average velocity 

 increases in direct ratio with the angle of movement. 



Guillery 1 observed a decided difference between the velocity of the 

 eye at the beginning and at the end of an eye-movement; but his 

 experimental method involved two conditions that tend to distort the 

 relation. In the first place, his eye-movements were uniformly ex- 

 treme, and involved considerably more muscle strain and effort than 

 the more natural excursions measured by Dodge and Cline, which 

 never exceeded 20 from the primary position of the eye. Still more 

 important is the fact that it is found to be impossible, even under the 

 most favorable conditions, to secure a series of simple direct movements 

 of the eyes from one fixation point to another which is more than 40 

 distant. This distance is persistently underestimated, and the initial 

 long movement of the first type is succeeded by a shorter corrective 

 movement of the same type. Since Guillery 's eye-movements were 

 all 40 or over, it seems probable that his attempt to measure the 

 velocity of the end of the eye-movements was confused by the small 

 corrective movements whose average velocity is comparatively low. 

 In the abductive movements, the photographic records commonly show 

 a marked difference between the velocity of corresponding portions of 

 the first and third phases. This peculiarity of the third phase is 

 sufficient to account for the longer duration of the abductive move- 

 ments as remarked independently both by Guillery, and by Dodge and 



Guillery, Archiv f. d. ges. Physiol., 1898, 73, p. 87. 



2 Briickner, Archiv f. d. ges. Physiol., 1902, 90, p. 73. 



'Erdmann and Dodge, Psyehologische Untersuchungcn iihor das Lesen, Halle, 1898. 



