26 Walter Frank Raphael Weldoti. 1860—1906. 
Unfortunately the paper, as well as the suggestive " Remarks on Variation in 
Animals and Plants" (18), with its memorable words : — "The questions raised by 
the Darwinian hypothesis are purely statistical, and the statistical method is the 
only one at present obvious by which that hypothesis can be experimentally 
checked " — fell on very barren soil. The paper produced a mass of criticism — 
folios were written to the Chairman of the Committee, showing how this, that 
or the other vitiated entirely the results. The very notion that the Darwinian 
theory might after all be capable of statistical demonstration seemed to excite all 
sorts and conditions of men to hostility. Weldon, instead of being allowed to do his 
own work in his own way, had to be constantly replying to letters, some even 
eighteen sheets long, addressed to the Chairman of the Committee. These letters 
were not sympathetic and suggestive, but mostly purely controversial. The 
need for further investigation of the law of growth had been frankly admitted by 
Weldon in the " Remarks " issued at the discussion on the " Report," but the 
critics declined to wait for answers till further results were published. This 
attack lasted for the next three years, during which further researches on the 
selective death-rate and growth of crabs were carried out, and it formed a serious 
impediment to calm progressive investigation. A further instructive report (19) 
on the growth at two moults of a considerable number of crabs was made to 
the Committee in 1897, but I believe has never been published. Later, an 
account of work on Natural Selection in crabs was given by Weldon in his 
" Presidential Address to the Zoological Section of the British Association," 
Bristol, 1898 (20). 
In this paper Weldon returns to the problem of whether frontal breadth 
in crabs is correlated with a selective death-rate, but he now deals with type and 
not variability. He first approaches the problem from the consideration of 
whether for this character the crabs in Plymouth Sound are remaining stable, and 
he shows from measurements made by Sir Herbert Thompson and himself during 
the years 1892 to 1896, that the population is unstable. He next seeks a cause 
for this secular change, and he finds it in the tui'bid state of the water in 
Plymouth Sound, due to the continual carriage into it of large amounts of china 
clay and sewage. Direct experiments were then made on the selective death-rate 
of crabs kept in water with suspended china clay and on another occasion in foul 
water. In all cases the survivors were found to have a smaller frontal breadth 
relatively to their carapace length. Confirmatory experiments showed that after 
the first shock of confinement was passed this selection did not occur among crabs 
kept in pure sea water. A reasonable explanation of this selective action was 
provided in the character of a crab's breathing apparatus. Thus, after several 
the mathematical standpoint, I still think them valid, but I realise also how much of my own work 
flowed directly from the suggestiveness of this paper. In fact it was the starting-point of the whole of 
the work on the influence of selection on the correlation and variability of organs. The sequel to that 
work, the influence of selection during growth, flows equally from Weldon's paper, but although we 
know much more than we did ten years ago as to the laws of growth, no sufficiently general formula of 
growth can yet be applied to allow of the completion of Weldon's work in this direction. 
