LVIII BOWMAN LECTURE. 



and at the same time to indicate some of the directions in 

 which further reseach into their nature is most needed. 

 Many, such as the heredity of errors of refraction and 

 of the musculature of the eye, I cannot touch. We 

 could all cite plenty of examples showing the family 

 prevalence of both these classes of defect, but I do 

 not think much has yet been done in the direction most 

 suitable for clinical observers the careful record and 

 analysis of individual pedigrees. The elaborate statistical 

 enquiry upon the inheritance of arnetropia lately brought 

 out by Professor Karl Pearson and Miss Amy Barrington* 

 will help to elucidate the ever-present problem of environ- 

 ment versus heredity in the causation of myopia, although 

 the imperfection of the data (data derived from ophthalmo- 

 logical examinations, be it confessed) often detracts from 

 their value to the biometrical statistician. 



I shall say but little on the theoretical side of my 

 subject, being, as I am, quite unable to deal with the 

 biological and mathematical complexities in which the 

 modern student of heredity finds himself involved. As 

 one who must be content with a very modest share of 

 spade work I am grateful that in the medical domain 

 there is still virgin ground where the tasks of ex- 

 cavating, collecting and recording may be safely under- 

 taken by those who enjoy them. And here I wish 

 to express my deep indebtedness and cordial gratitude 

 to the many colleagues and friends who have generously 

 furnished me with cases and numerical records bearing 

 upon heredity, and have, often at much tedious trouble 

 to themselves, aided me in the collection and disen- 

 tanglement of genealogical details. I could have done 

 next to nothing without such help. 



Before getting to close quarters with individual diseases 

 I must ask your indulgence whilst, in order to avoid need- 

 less repetition, I refer to certain generalities. 



* " A First Study of the Inheritance of Vision and of the Eelative 

 Influence of Heredity and Environment on Sight." By Amy Barrington 

 and Karl Pearson, F.R.S., Eugenics Laboratory Memoirs, v, 1909. London : 

 Dulau and Co. 



