ANATOMICAL STRUCTURE OF ANTHROPOID APES. 95 



The eye of the young male gorilla which was 

 kept alive in the Berlin Aquarium from 1876-77 

 was carefully examined by me in June, 1877. I 

 found that the sclerotic membrane of the eyeball 

 was whitish, surrounded by a dark brown ring. A 

 second darker ring, sharply defined, surrounded the 

 cornea. The iris was of a yellowish brown. The 

 sclerotic membrane, however, gradually deepens in 

 colour so as to give the effect of a uniform dark brown. 

 The iris retains a light brown colour for a longer 

 period, but it darkens with age. In an aged animal 

 there is no brightness in the eye, except from reflected 

 light. In the chimpanzee the iris is light brown, verg- 

 ing on yellow; and this is also the case in the oraug. 



The expressionless, indifferent look of anthropoids 

 has often been observed, and undoubtedly chimpan- 

 zees and orangs generally gaze placidly before them. 

 I have, however, observed an animated expression 

 in the eyes of the former species, and W. L. Martin 

 has also observed a flash and brightening of their 

 eyes. I shall never forget the expression of 

 malicious auger in the eyes of the feajale animal 

 Mafuca, at Dresden, as soon as she was teased. The 

 expression of the eyes of the gorilla in the Berlin 

 Aquarium also changed frequently, especially when 

 he was about to perform some mischievous trick, or 

 when he was provoked to anger. The expression of 

 this animal was very human, but necessarily it could 

 only recall the darkly coloured eyes of negroes and 

 other black races. In 1876 there were two very 

 young orangs in the Berlin Aquarium, one hairy and 

 the other hairless. These animals clung together in 



