Febeuaey 25, 1898.] 



SCIENCE. 



271 



ttirn when closed. The mixed lines show 

 the actual direction of the eyes when closed 

 and at the instant of opening. The com- 

 plete lines show the direction of the axes of 

 the eyes when open. A represents in both 

 cases the eye closed, the object. 



There is one case which offers some difi&- 

 culty to this explanation ; unless, indeed, 

 it is to be regarded as an illustration of the 

 general principle formulated above that re- 

 laxation is inversely proportional to the 

 effort of convergence. If, as in the instance 

 represented in the second figure, the object 

 be far to the right, but be fixated with the 

 right eye rather than with the left, and then 

 the left eye be closed and opened, we 

 should naturally expect crossed images in- 

 dicating convergence beyond the object". 

 I have sometimes found this to be the case. 

 Sometimes, however, I have observed no 

 double images, or even at times uncrossed 

 double images. It would seem that in these 

 cases the closed eye in its strained position 

 may be converged too much. This, how- 

 ever, is observable only at times ; the regu- 

 lar results are double crossed images. 



So far as convergence is concerned the 

 open eye exerts the controlling influence ; 

 its position remains unchanged. But in 

 accommodation the relaxation of the closed 

 eye has an important influence on the ac- 

 commodation of the open eye. If an object 

 is fixated with both eyes, and moved away 

 to the limit of distinct vision, it will be 

 found on closing one eye that the outlines 

 are no longer distinct. It is, for example, 

 impossible to read print with one eye at a 

 distance to which it could be just clearly 

 seen with both eyes open. The figures on the 

 moon grow very indistinct when one eye is 

 closed. This indistinctness may be due, in 

 part, to the enlargement of the pupil, for 

 the pupil of the open eye is very much 

 enlarged in sympathy with that of the 

 closed. But this cannot be the whole ex- 

 planation. For when one eye is covered up 



in such a way as not to exclude the light 

 entirely the pupil of the fixating eye is not 

 affected as much. The outlines, however, 

 are indistinct even in this case, showing 

 that the accommodation of the lens has un- 

 dergone a change. Whether this change in 

 the lens is one resulting in greater or less 

 convexity I have not succeeded in deter- 

 mining. The fact that a voluntary accom- 

 modation for a nearer point does not, in my 

 case, make the object clearer, but rather 

 the contrary, would seem to lead to the con- 

 clusion that the lens has become more con- 

 vex rather than less so. Yet this does not 

 appear to be conclusive. The main fact, 

 however, is that there is some change in 

 the accommodation of the lens of the open 

 eye when one eye is closed. 



The bearing of these facts on many ex- 

 periments in optics will be apparent. Wundt 

 denies complete binocular convergence when 

 one eye is closed, while Hildebrandt and Ar- 

 rer* maintained the opposite. The truth 

 seems to be that the closed eye follows the 

 open eye to a certain extent, and to a cer- 

 tain extent obeys its own tendencies of re- 

 laxation. There is a change in the size of 

 the pupil in both eyes and a change in the 

 accommodation of the lenses. 



Chas. H. Judd. 



Wesleyan Univeesity. 



A NEW NAME FOR THE NOVA SCOTIA FOX. 



In the proceedings of the Biological 

 Society of Washington, Vol. XI., March 

 16, 1897, pp. 53-55, I described the large 

 red fox that occurs in Nova Scotia (and per- 

 haps other parts of the Canadian and Hud- 

 sonian zones in eastern North America). 

 Unfortunately, I used the subspecific name 

 vafra that is already in use for a fossil fox 

 — the Canis vafer Leidy (Ext. Mam. Faun. 

 1869, p. 368). 



It therefore becomes necessary to re- 



* ' Philosopliisohe Studien,' XIII., p. 116 seq. 

 Other references given in the same p'ace. 



