The Evolution of Optics 283 



in the part that blood has played in the world's history. 

 Throughout the long struggle for existence among the 

 higher animals bloodshed has ever been the constant ac- 

 companiment of strife, has stained the weapons of the vic- 

 tor, marked the defeat of the conquered. 



Throughout the history of all religions and all social cus- 

 toms we find that blood has always played a most important 

 part. We read of " the blood-drinking, blood-baiting, blood- 

 ransoming, blood unions, blood compacts and friendships, 

 blood sacrifices and blood suppers, blood burials, blood cures 

 and sprinklings, bloody hands and uplifted arms, blood 

 transfusions, human sacrifices and cannibalism, bloody 

 burnt-offerings and blood-stained ark of the covenant, 

 bloody passions and bloody atonements " ; and thus through- 

 out the long and passionate strife of mankind has the red 

 burned itself deep into the human soul and has come to oc- 

 cupy this prominent position in our estimate of color while 

 only possessing that luminous intensity to which its com- 

 parative infrequency in nature would entitle it. "The 

 portion of spectral blue is small in extent and weak in 

 power. It has a character of distance and impersonality, 

 exactly corresponding to the sources whence this color has 

 reached the eye. The sky is above, but man's eyes are sel- 

 dom raised to it. At the horizon it often fades into violet, 

 in which the spectrum likewise passes out of sight." 



Dr. Gould concludes : " "Waves of more or less extended 

 differences of length are perceived as a single color, just as 

 the bulk of the waves from each of these classes of objects 

 have been most uniformly and persistently reflected into the 

 eye during the growth of the race. Nature has acted upon 

 the organism in these continuous ways, and the cerebral 

 product is the spectral colors in the proportions and with 

 the characteristics we find appearing in consciousness. The 

 largest and most persistent stimulus has been that of the 

 gold rays the varied shades of the diffused light of day or 

 the ever-present mystery of fire. These have been poured 

 in profusion into all eyes, comprising nearly one half of 

 their total stimulus, while the green rays make up a fourth, 

 the red less than a fourth, and the blue a still more limited 

 amount." 



"We likewise find the objective luminous intensities to 

 bear the same relations to each other. 



"We can not enter further into this interesting discussion, 

 but I think we may safely assume that this theory offers 



