POWERS OF VISION. 123 



rapidity of the contraction and dilation of the pupil with the 

 enlargement, perhaps, of tlie retinal receiving area. It is, however, 

 a noteworthy circumstance that these natives are able to pass from 

 the bright tropical glare outside their dwellings to the dark in- 

 teiiors, and vice versa, without showing that temporary derangement 

 of vision which the white man experiences whilst the iris is 

 adapting itself to the new condition. 



My attention was not attracted by the size of the pupils ; but I 

 paid no especial attention to this point. ^Ir. J. Eand Capron in the 

 correspondence in " Nature," above alluded to, refers to the circum- 

 stance that the pupil varies in size in individual cases ; and he 

 instances the case of one of his assistants possessing unusually large 

 pupiLs who had a singularly " sharp " eye for picking up companions 

 to double stars, small satellites, &c., and who could read fine print 

 with a light much less bright than is usually required. "The 

 peculiarity afiecting my assistant's eyes," as Mr. Capron writes, 

 " may be more common with the savages than with us." I am in- 

 clined myself to believe that, on a careful comparison being made, 

 the pupils of the savage will be generally found to be larger. If 

 such should be the case, we shall have a ready explanation of his 

 better discriminating powers of vision. 



The eyes of these natives have usually a soft, fawn-like appear- 

 ance with but little expression. Of the twenty-two individuals 

 whose sight I examined, I came upon only one whose powers of 

 vision seemed at all defective. In this instance — that of a man 

 about thirty years old — the nature of the cause was sufficiently 

 indicated by the prominence of the ej'es and the nipping of the lids, 

 especially when the sight was strained by trying to count the test- 

 dots at a distance. The limit of distance at which this man could 

 count the test-dots was 35 feet. The question which presented 

 itself to my mind in this case was, whether a white man, who could 

 count the dots at the same limit of distance, would exhibit to the 

 same degree the external signs of myopia. 



I also made some observations on the colour-sense of the in- 

 habitants of Bouorain^^lle Straits. Althouoh. able to match the 

 seven colours of the spectrum, viz., red, orange, yellow, green, 

 Prussian blue, indigo, and violet, they have only, as far as I could 

 ascertain, distinctive names for white, red, yellow, and sometimes 

 blue ; whilst all the other colours, including black, indigo, dark blue, 

 violet, (jreen, &c., are included under one or more general names for 



