OBSERVATIONS AND EXPERIMENTS ON VISION. 3^5 



brane. He now applied the juice of belladonna to his 

 left eye. Half an hour after, when his pupil was but 

 little dilated, perfect vision commenced at the distance of 

 iseven inches; in fifteen minutes more, it began at the dis- 

 tance of three feet and a half. When his pupil had acquired 

 its greatest enlargement, the rays from the image of the 

 flame of a candle, in the bulb of a small thermometer at 

 the distance of eight feet, could not be prevented from con- 

 verging to a point behind the retina. The rays from lamps 

 still more distant, and from stars, had their focusses at the 

 same time on the retina. This state of vision continued, 

 in its greatest extent, to the following day; and it was not 

 till the ninth day after the application of the belladonna, 

 that he completely recovered the power of adapting his 

 eye to near objects. While his left eye was thus affected, 

 the vision of the right remained unaltered. 



Dr. Cutting remarked, while his left eye was returning to Dilatation of 

 its natural condition, that the diminution of the pupil, and ^j^^yg p^^. 

 the increase of the range of perfect vision, did not keep portio"al to the 

 regular pace with each other ; but that, after his pupil had 

 nearly returned to its former size, his capacity of adapting 

 the eye to different distances was still very limited. As 

 these effects therefore are not inseparably connected, they 

 may occur in others in a different manner from that which 

 he observed. A great degree of dilatation, for example, 

 may take place in the pupil, without a total want of the 

 power to adapt the eye to different distances. 



Though I could not doubt the accuracy of Dr. Cutting's The experi- 

 obscrvations, more especially as the altered state of his ^^^Jl'the othet 

 eye had lasted a considerable time, and as he had not been eye. 

 prevented by other occupations from attending minutely to 

 the appearances, which were consequent upon it; yet, as ' 



he was the first person who had ever applied belladonna to 

 his eye, for the purpose which has been mentioned, and as 

 the results had been remarkable, I requested him to repeat 

 the experiment with his other eye. He complied with my 

 desire, and found, that the appearances which followed 

 were similar to those, which had been produced by the ap- 

 plication of belladonna to his left eye. 



It 



