OUR FACE FROM FISH TO MAN 



oval plaque with its long diameter inclined 

 obliquely from above downwards and from within 

 outward. Le Double further notes' that during 

 intrauterine life the human lacrymal is successively 

 oval, triangular and quadrilateral in form, that 

 the lacrymal of the gorilla is almost triangular, 

 while those of the adult chimpanzee and orang, 

 which show so much resemblance to the human 

 lacrymal, are also subject to the same variations 

 in form. 



CONCLUSIONS 



In conclusion, the human eyes owe their begin- 

 nings to the sensitivity of protoplasm both to the 

 injurious and the beneficial effects of light. In 

 their early pre-vertebrate stages they seem to 

 have been merely directional organs to orientate 

 the animal's locomotion with reference to the 

 light, serving the same purpose at the lower sides 

 of the head as the pineal and parapineal eyes did 

 on the top of the head (Fig. 97A). At this stage 

 the eyes were still on the inner side of the brain 

 tube. When the brain grew outward into contact 

 with the epithelium the optic cup acquired a lens 



Ibid., pp. 128, 129. 



200 



