50 EVOLUTION OF THE HUMAN EYE 



becomes discovered by the small diurnal birds upon which 

 he usually preys, they at once recognize his plight and give 

 him no mercy, mobbing him and pecking him with impunity. 

 Thus through the specialized character of the end-organs 

 of the retina the mighty hunter of the night becomes the 

 abject victim of the day. 



Primitive man, having abandoned the safety of the trees, 

 sought protection from the perils that prowl by night in 

 the natural recesses of the cliffs, and became a cave-living 

 animal. Gradually he progressed to the hollowing out of 

 caves for himself, and thus acquired the first step which 

 led to the building habit. From this may we not trace the 

 construction of lake dwellings, which by their situation 

 afforded admirable protection from carnivorous foes, and 

 later the more substantial houses of brick and stone, ulti- 

 mately leading to all the glories of architecture? 



It is probable also that fire, when first discovered by 

 primitive man through hacking iron pyrites with a flint 

 among dead leaves (Lubbock), was more valued for its 

 illuminating than its heating properties. By the illumina- 

 tion which it afforded him at night his range of vision would 

 become extended, and his struggle for existence against 

 carnivorous mammals considerably assisted. From this 

 first use of fire as an illuminant we can trace man J s gradually 

 increasing means of overcoming the dangers of darkness, 

 until we arrive at the powerful searchlight of today which 

 he employs both for purposes of attack and defence. 



