262 Mr Punnett, 



On Nutrition and Sex-determination in Man. By R. C. 

 Punnett, M.A., Gonville and Caius College. 



[Bead 26 October 1903.] 



Of the various factors which have from time to time been 

 brought forward to account for the determination of sex, that 

 of nutrition appears to have found most favour. That favourable 

 nutritive conditions tend to produce females, and unfavourable 

 conditions males is a hypothesis which has received much support 

 from observation and experiment on numerous forms of life 1 . In 

 the case of the human species, however, strong evidence for or 

 against this view is yet a desideratum. The idea of the writer 

 of this paper was to consider the population of a large city divided 

 up into areas differing in poverty or wealth (a factor greatly 

 affecting nutrition), and to estimate the relative proportion of 

 male and female infants in each of them. That out of the enquiry 

 certain other points not devoid of interest have arisen, it is hoped 

 will appear in what follows. 



Though it is a matter of common knowledge that the food 

 of a large proportion of the working classes is not always sufficient 

 in quantity, more exact information has been difficult to come by. 

 Quite recently, however, Rowntree 2 has published an invaluable 

 work on the subject, where he deals very thoroughly with this 

 question. The main conclusions at which he arrived may be best 

 presented in his own words. He has in this case divided his 

 population into three classes, i.e. (1) the servant-keeping class, 

 (2) the artisan class where the family earnings are over 26/- a 

 week, (3) the labouring class earning less than 26/- a week per 

 family. The standard diet with which he compares the diets 

 of these three classes contains 125 grams of proteids, and has a 

 total energy value of 3500 calories. As the results of his enquiries 

 Rowntree 3 concludes that : — 



(1) The diet of the servant-keeping class is, upon the whole, 

 in excess of that required for the maintenance of health. 



(2) It is probably safe to assume that, in the case of average 

 families of the artisan class, the food supply is adequate, although 

 it is clear that in many cases it can only continue so by abstention 

 from wasteful expenditure upon drink, &c. 



1 Cf. Geddea and Thomson, Evolution of Sex, 1st Edition, pp. 41 — 47. 



2 B. S. Rowntree, Poverty, A Study of Town Life, 2nd Edition, 1902. 



3 loc. cit. p. 259. 



