BOWMAN LECTURE. CXXV 



and incomplete even in them. I put the same inter- 

 pretation on Fig. 55 (Albinism Memoir, Fig. 410, my own 

 case, Mansfield), and Figs. 187 and 188, Appendix VII.* 

 The note of all these cases is the blue or grey iris, 

 hair now brown, but with the history that it was very 

 fair or even " white " in early childhood, and a more or 

 less albinotic fundus ; almost all have nystagmus and 

 marked arnblyopia; when, as in a few of the cases, sight 

 is good and the eyes steady, we must suppose that the 

 retinal epithelium, at least at the yellow-spot region, is 

 sufficiently pigmented, however lacking in pigment the 

 choroid may be.t 



* The suggestion that the cases just mentioned, and others like them 

 were of albinotic nature was made, so far as I am aware, for the first time 

 by myself in R.L.O.H., xv, p. 110, 1902. It is evident that the idea of 

 albinism was present to the minds both of Mr. Lloyd Owen in connection 

 with Fig. 54 in 1882 and myself in relation to Fig. 55 in 1887, but it was 

 mentioned by each of us at those dates, only to be dismissed. 



t The hypothesis is that the imperfect sight, and with it the nys- 

 tagmus, is caused by deficiency of pigment in the retinal epithelium ; 

 that this want may vary in degree, and may even, perhaps, affect only a 

 part say the central region of the fundus ; and lastly, that such 

 relative or absolute lack of pigment in the epithelium is not recognisable 

 with any certainty by ophthalmoscopic examination, the different depths 

 of tint at the fundus depending far more upon differences of pig- 

 mentation of the choroid than of the hexagonal epithelium. In support 

 of this speculation we may say (1) that in albinism with quite trans- 

 lucent iris, i. e. no pigment in the retinal layer, stroma pigment is occa- 

 sionally present in sufficient quantity to give the iris an ordinary brown 

 colour; (2) that microscopical examination of the choroid of normal 

 European eyes shows in the comparatively small number of specimens 

 where attention has been carefully directed to the point that the 

 quantity of pigment in the retinal epithelium appears to be sensibly the 

 same in eyes with pigmented iris and choroid as in those with iris 

 and choroid almost, or quite, devoid of stroma pigment. Whether this 

 position will be maintained when a larger number have been examined 

 remains to be seen. Also we must be careful, for the present at least, to 

 allow for probable differences in the kind of pigment in the eyes of 

 European and of dark races ; the eye-pigment of a Negro may be darker 

 than that of a Scandinavian although the qviantity be the same in the 

 two. These are nice, but important, problems for future determination, 

 and I have reason to believe that work is already in progress upon them. 

 Examination of partly albinotic eyes, the so-called " wall eyes " or pie- 

 bald eyes they might be called, of dogs and horses by Mr. Coats and Mr. 



