THE PERCEPTION OF LIGHT 



613 



Figs. 758 to 760. — The Contractile Pupils of Placentals. 



Fig. 758. 



Fig. 759. 



Figs. 758 and 759. — The pupils of the cat m dilatation (Fig. 758) and in 

 conti'action showing the_^extremely narrow vertical slits (Fig. 759). 



Fig. 760. — The tarsier, Tarsius, to show the jaupils in contraction ; they are 

 horizontal slits but practically circular (johotograph by Douglas Fisher). 



