248 J. LEJEUNE AND M.-O. KETHOKE 



ANALYSIS OF DATA 



For tlie actual analysis three characteristics have been selected, out of the 

 ninety recorded for each individual. 



1. Segmentary heterochromia of the iris 



A segment, delineated by the pupiUa, two radii and the corresponding 

 peripheral arc of the iris, is found to be uniformly in tone colour different 

 from the rest of the iris. This miilateral trait looking like a "slice of cake" can 

 be detected very safely and was known by the parents in most instances. All 

 cases reported by our visiting students, have been controlled secondarily by 

 an ophthalmologist. Many combinations of colours have been found, dark on 

 blue, or white on dark. 



2. Dark lock in fair-haired children 



In three instances (aU three irradiated) a lock, the size of 1 to 2 cm on the 

 skm, was dark in contrast with the rest of the blond hairs of the neck. The 

 skin itself did not show any abnormal pigmentation at the site of implanta- 

 tion of the dark lock. 



3. White forelock 



This very characteristic dominant trait was used as a control for the 

 internal consistency of our data. Being related to one gene mutation, and 

 bemg aheady well spread throughout the population, such a characteristic 

 should not be influenced by X-rayuig the foetus, at least with the very low 

 doses received. 



Table I. Total number of persons examined in the two enquiries 



„ , , Heterochromia t^ , , , White 



lotal n- ■ Dark lock r , , 



ol iris lorelock 



Table I shows: 



(i) No relationship between irradiation in utero and frequency of the white 

 forelock. This expected negative finding is in favour of no selection in the 

 irradiated group. 



(ii) The dark lock is much more common in the irradiated than among the 

 unirradiated. 



