OUR BEST FEATURES 



Optical Photography and its Results 



THE human eyes AS INSTRUMENTS OF PRECISION 



All sense organs are instruments of precision 

 that register varying intensities of the pulsing 

 streams of energy to which they are exposed. 

 The paired eyes of man, together with their con- 

 nections in the central nervous system, register 

 even slight changes in the intensity of light, they 

 respond to a wide range of its wave length, and 

 hence discriminate colors, and they are extremely 

 sensitive to the movement of images across the 

 retina. Through their binocular adjustments they 

 record extension, relative distances, and move- 

 ments in a three-dimensional field, and by their 

 bicon jugate movements they can find a moving 

 image and keep it in focus within wide limits. 



THE EYES OF INVERTEBRATES 



The anatomy and physiology of the eyes of 



invertebrates and vertebrates are the subjects of 



an enormous literature, which has been admirably 



summarized by L. Plate in his Allgemeine 



Zoologie und Ahstammungslehre, Zweiter Teil, 



Jena, 1924, wherein are set forth more fully most 



173 



