THE VERTEBRATE EYE 11 



The iris varies with respect to its color in different indi- 

 viduals. The posterior border (retinal portion) is heavily 

 pigmented. In white races, the stroma is relatively free 

 from pigment at birth. Light piercing the transparent an- 

 terior layers is reflected back and owing to the phenomenon 

 of interference, the color appears blue. If no pigment de- 

 velops in the anterior border layers, the iris remains blue 

 except in the regions occupied by blood vessels which are 

 not transparent. With moderate amount of pigment de- 

 veloping in the anterior border layer, the color becomes 

 gray; with the development of much pigment in this layer 

 the color becomes brown. 



In connection with variations in the iris it is of interest to 

 quote from Duke-Elder (1939). ''So great are the individual 

 variations of the architecture of the iris that these were long 

 ago suggested as a basis for the identification of criminals 

 (Bertillon, Rev. Sc, XXXVI, 65, 1885), a practice which 

 has lately been revived. Nor has imagination and super- 

 stition failed to clothe it with significance; Tenon saw the 

 letter T in many, while the name of the Emperor Napoleon 

 or other characters more mystical used to be deciphered. 

 Even today an extraordinary cult with a considerable follow- 

 ing and a voluminous literature flourishes, particularly in 

 Central Europe, the devotees of which attribute to each 

 minute area of this tissue an affinity for a different organ in 

 the body, in the list of which the eye itself is included, and 

 from an examination of the appropriate area the initiated 

 can diagnose any disease to which flesh may fall heir. They 

 call themselves oculodiagnosticians ('irido-diagnosis,' ' Augen- 

 diagnose,' etc.). (See Gilbert, 1924; Mondain, Tilmont and 

 Benoit, 1924)." 



In this connection it might be of interest to cite the ex- 

 traordinary case of John Woods which is reproduced on the 

 following page from Ballantyne's (1904) Antenatal Pathology 

 and Hygiene (Figure 22). 



