SCIENTIFIC PROCEEDINGS. 



Abstracts of Reports. 1 



Eighth meeting. 2 



Physiological Laboratory of Columbia University, at the College 

 of Physicians and Surgeons. October ip, ipo/j.. President Meltzer 

 in the chair. 



i (47). 3 " The accommodation of the eye," with demonstrations : 

 THEODOR BEER, of the University of Vienna. (By invita- 

 tion.) 



Two principles are realized in the accommodation of an eye that 

 is constructed as a " camera obscura": (1) Change of curvature 

 of refracting surfaces, principally the lens ; (2) change of distance 

 between refracting mediums and image screen, principally distance 

 between lens and retina. 



1. There is only increase of curvature, principally of the anterior 

 surface of the lens, during active accommodation. We observe it 

 in mammals, birds, and reptiles (lizards, crocodiles, turtles, a few 

 snakes). Experiments were made before the society to show the 

 increase of curvature of the lens in the eye of the water-turtle — 

 proof of Helmholtz's theory of accommodation. 



2. Accommodation by change of the distance between lens and 

 retina is possible in two directions : (a) In cephalopods and fishes, 

 which are normally shortsighted, accommodation for objects at a 

 distance is effected by a movement of the lens toward the retina. 

 In the eye of the fish there is a muscle Musculus retractor lentis 

 (Beer) which draws the lens toward the retina ; (b) in amphibia 

 and most of the snakes, the lens is moved toward the cornea, away 

 from the retina, by changes of the intraocular pressure. 



1 The authors of the reports have written the abstracts. The editor has made a 

 few abbreviations and minor alterations in some of them. 



2 Reprinted from Science, 1904, xx, p. 677; American Medicine, 1904, viii, p. 

 931 ; Medical News, 1904, lxxxv, p. II43. 



3 See Preface. 



19 (S3) 



