THE COLOUR VISION OF PRIMITIVE RACES 149 



Mg or Mthiti, black. The nomenclature for violet and brown was very 

 indefinite. There was a definite name for white, and greys were called 

 white or black, or occasionally " ashes," a common term for this colour 

 in Southern India. 



Rivers tested 503 Todas with Holmgren's wools : 43 were found to 

 be definitely colour-blind. The normal individuals matched the wools 

 well, but most confused red and pink, green and blue, violet and blue, 

 and there was a general tendency to confuse faintly coloured wools. 

 One confused blue with grey and brown, and two blue with brown. 

 The defects of this kind were less marked than among the Uralis 

 and Sholagas examined in India 1 and the Egyptians. All showed a 

 tendency to discriminate greens, blues, and violets less definitely than 

 reds and yellows, indicating that the deficiencies in nomenclature for 

 the former group of colours were accompanied by a certain degree of 

 deficiency in their discrimination. 



Quantitative observations on the colour thresholds were made with 

 Lovibond's tintometer. The table gives the results obtained by Rivers 

 in five different communities. 



No. ex- 

 amined. Red M.v. cr C.V. Yellow M.V. a C.V. Blue M.V. a - C.V. 



Todas .. 47 32'1 18'] 24'3 75'5 29'2 156 21'3 73'1 53'3 20'7 23'4 44'0 

 Uralis and Shola- 

 gas .. 14 31-1 13-5 16-6 53-4 26'4 7'9 8'7 33'1 66'4 15-5 17'6 26'4 

 Egyptians 26 28'7 14'2 15'8 55'3 26 -0 10'5 12'3 47'5 85'4 34'3 43'4 50'9 

 Murray Islanders 17 17'6 7'5 8'9 50'6 26'8 9'9 11'6 43"0 60'0 16'5 20'2 33'6 

 English .. 41 27'5 17'9 21'7 79'0 16'7 7'2 lO'O 60'1 30"8 11-2 14'9 48'4 



In this Table the average thresholds, expressed in units of the 

 instrument, are given in the columns headed by the names of the colours. 

 The figures under the heading M. V. give the mean variations of the 

 results of the individuals of each group from the average result of that 

 group. Under a are given the standard deviations 2 of the individual 

 results from the average ; under C.V. the coefficients of variation as 

 worked out from the formula 



o-xlOO 

 Average ' 



This table shows that the Todas have the highest thresholds for 

 red and yellow obtained in any community hitherto tested. The 



1 Bull. Madras Gov. Museum, v. 3, 1903. 



/28 s 



2 I.e., v / , where 25 is the sum of the squares of the individual differences S l , 5 2 , . . , 



from the mean, and n is the number of individuals. 



