Walter Frank Raphael Weldon. 1860—1906. 
19 
latter city, and the first biometric crab paper "On certain correlated Variations in 
Carcinus moenas " (15) was issued in this year. In this paper Weldon confirms on 
the shore crab his results for the common shrimp. The distributions of characters 
are closely Gaussian with the exception of the relative frontal breadth, which 
Weldon considered dimorphic in Naples, a problem which led to the present writer's 
first paper in the Gontribidions to the Mathematical Theory of Evolution. It is right 
to say that Weldon had reached a moderately accurate solution by trial and error 
before he proposed the problem to his colleague. He does not refer to this fact 
in his memoir. As for shrimps the correlations again came out closely alike for 
the Plymouth and Naples races. Weldon was not dogmatic on the point ; he 
considered the constancy as at least an " empirical working rule " and this it has 
certainly proved. 
"The question whether this empirical rule is rigidly true will have to be determined by fuller 
investigation on larger samples ; but the value of a merely empirical expression for the relation 
between abnormality of one organ and that of another is very great. It cannot be too strongly 
urged that the problem of animal evolution is essentially a statistical problem : that before we 
can properly estimate the changes at present going on in a race or species we must know 
accurately (a) the percentage of animals which exhibit a given amount of abnormality with 
regard to a particular character ; (b) the degree of abnormality of other organs which accompanies 
a given abnormality of one ; (c) the difference between the death rate per cent, in animals of 
different degrees of abnormality with respect to any organ ; {d) the abnormality of offspring 
in terms of the abnormality of parents and vice versa. These are all questions of arithmetic ; 
and when we know the numerical answers to these questions for a niimber of species we 
shall know the deviation and the rate of change in . these species at the present day — a 
knowledge which is the only legitimate basis for speculations as to their past history, and 
future fate." 
These concluding words were surely epoch-making ; they formulated the 
fundamental principles of biometry. We may criticise the memoir in that the 
index measurements selected by Weldon overlooked the question of spurious 
correlation, or because the growth law of the indices had not been previously 
determined. But these are minor matters compared with the general ideas 
involved in the memoir. It is a paper which bioraetricians will always regard as 
a classic of their subject. It first formulated the view that the method of the 
Registrar-General is the method by which the fundamental problems of natural 
selection must be attacked, and that is the essential feature of biometry. 
Besides biometry a new bond drew Weldon and the present writer together. 
Since 1884, a strong movement for the reform of the University of London had 
been in progress, association followed on association, royal commission on royal com- 
mission. Few people had distinct ideas of what they themselves wanted, scarcely 
any one had a notion of what a real university must connote. At University 
College, after severe crises, the teaching staff had won direct representation on 
the governing body, and was beginning to insist upon being heard in the question 
of university reform. One of the most vigorous protagonists in this matter was 
Lankester, and his removal to Oxford threatened the little group who had definite 
notions of academic reform with complete defeat. Luckily Weldon joined us 
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