THE SENSE ORGANS 



149 



pure Negroes this cartilage was found by Giacomini in twelve 

 individuals. 



The plica semilunaris varies greatly in size at different ages 

 and in different races. In the new-born child, and during the 

 early years of life, it is broader than later, when it does not exceed 

 1 to 2 mm. in breadth. One known exception to this rule is, 

 however, found in the Malay tribe of the Orang-Sakai, in which it 

 reaches a breadth of 5 to 5| mm. It would be worth while to 

 examine other tribes in this respect. 



In the caruncula lachrymalis (c.l., Fig. 91), which lies near the 

 plica semilunaris, glands are to be found, which in their structure 



FIG. 92. DIAGRAM TO ILLUSTRATE THE SHIFTING OF THE LACHRYMAL GLAND, 



WHICH HAS TAKEN PLACE IN THE COURSE OF PHLYOGENY. 



The gland shifts in the direction of the arrows ; a, its position in the Amphibian ; b, in 

 Reptiles and Birds, and in certain human beings, in which case it may be regarded 

 as atavistic ; c, normal position in Man. 



greatly resemble the lachrymal glands. These " nictitating glands " 

 constitute a distinct series and are in no way connected with the 

 sweat and Mollerian glands (Peters). Further, sebaceous glands 

 and fine hairs are, in the Primates, found near the caruncula. 



Finally, a mention may be made of accessory lachrymal glands 

 which, with their ducts, occasionally lie near the conjunctival sac 

 at the lateral angle of the eye (cf. Fig. 92) i.e. in a position 

 approximate to that of the lachrymal glands of Amphibia and 

 Reptiles, and indicative of a gradual shifting of the lachrymal 

 apparatus in the course of Phylogeny. 



Long stiff hairs which occasionally appear in the median 



