Page:Popular Science Monthly Volume 59.djvu/61

Rh common form of the defect in civilized countries. Since red-green blindness exists in about 4 per cent, of the male population of Europe, one may conclude that this form of defective color sense was either absent or was much rarer than with us. I also failed to find a case of color-blindness in Kiwai and Mabuiag and among the Australian aborigines, although I met with three well-marked cases of red-green blindness among eight natives of the Island of Lifu, in the Loyalty Group.

As regards other colors, however, the case was different; blue and green were constantly confused, and also blue and violet. Either owing to lack of interest or to some actual deficiency in color sense, there was a distinct tendency to confuse those colors for which their terminology was deficient. I have also found this tendency to confuse green and blue in several other races.

The behavior of the people in giving names to colors also pointed frequently in the same direction. I have already mentioned that in Mabuiag there was a great tendency to invent names for special colors; on one occasion a man, who seemed to have a special faculty in this direction,-gave me as the name for a bright blue wool 'idiiridgamulnga,' which meant the color of the water in which mangrove shoots had been washed to make 'biiu,' an article of food. In this case there was a deliberate comparison of a bright blue with dirty water, and I frequently came across other instances of the kind, which seemed almost inexplicable, if blue were not to these natives a duller and a darker color than it is to us.

This view was confirmed by quantitative observations, made with Lovibond's Tintometer, which had been kindly lent to the expedition by Mr. Lovibond. When the native looked into this apparatus he sawtwo square patches of light, either of which could be colored in any intensity of red, yellow or blue by means of a delicately-graded series of glasses of those colors. The 'threshold' for each color was then determined by finding the most faintly colored glass which the native could recognize and name correctly. The results showed that the natives recognized a very faint red, a more pronounced yellow, and only recognized blue when of a considerable intensity. Similar observations made on a series of Englishmen showed greatest sensitiveness to yellow and somewhat less to red and blue. The results may be given more definitely in Mr. Lovibond's units of color; in Murray Island, red was perceived on the average at.18 units, yellow at.27 and blue at .60 while the average results for the English observers were .31, .30 and .36 respectively. These figures do not show anything approaching blue blindness, but they do show a relative insensitiveness to blue in the Murray Islander, as compared with the European. The former appears nlso to be relatively more sensitive to red.