A COMPARATIVE STUDY OF THE AREA OF 

 ACUTE VISION IN VERTEBRATES. 



JAMES ROLLIN SLONAKER, 



Fellow in Biology, Clark University. 



Introduction. 



This investigation has been pursued during the past three 



years in the Neurological Laboratory of Clark University under 



the direction of Dr. C. F. Hodge, to whom I am under great 



obligations for his assistance and encouragement. I am also 



^ . . . 



greatly indebted to Clark University for the apparatus and 



material which has made this work possible. 



Up to the present I have been engaged chiefly in a gross 

 comparison of the retina rather than in its minute histology, 

 therefore my aim will be, first, to sum up the results of others 

 and also to add my own; second, to correlate as far as possible 

 the habits of the animal with its visual apparatus. 



Since there are so many investigators who have written on 

 various phases of the eye, it will be impossible to mention all. 

 Reference, therefore, will be made to only a few of the most 

 important in the historical resume and literature on the subject. 



I have adopted the nomenclature of the German investigators 

 and called the structure corresponding to the macula lutea of 

 man the area. According to the position of the area or fovea 

 on the nasal or temporal side of the optic nerve entrance, it is 

 called area ox fovea nasalis or temporalis. 



Historical. 1 



On the basis of the methods of investigation employed, the 

 literature may be divided into three periods: (i) from the ear- 



1 The literature on this subject has been fully presented by J. H. Chievitz 

 (Ueber das Vorkommen der Area centralis retinae in den vier hoheren Wirbel- 

 thierklassen, Arch. f. Anat. u. Entwickelungsgeschichte, 1S91, Heft 4, 5, u. 6, pp. 

 311-321), but as I have not found it anywhere in English, I will devote some space 

 to it. 



