32 
Walter Frank Raphael Weldon. 1860—1906. 
to another. No rapidly made measurement on the outside of the shell would 
satisfy Weldon ; the shell must be carefully ground down through the axis, and 
measurements made on the section thus exposed. Perhaps four or five snail shells 
could be ground and measured in a day, and at the time of his death, not more 
than a few hvindred of the Sicilian thousands had even been ground. Like the 
Dapknia, the Sicilian snails remain as an indication of the way — the path of 
absolute thoroughness — the master would have us follow. " Life is not long 
enough for biometry," murmurs the superficial critic. But the man of deeper 
insight replies : 
That low man goes on adding one to one, 
His hundred's soon hit : 
This high man, aiming at a million, 
Misses an unit. 
But these attempts to get to the kernel of selection in its action on local races 
were far from occupying the whole of Weldon's thoughts in these early days. In 
conjunction with his assistant, Dr E. Warren, he had commenced at University 
College his first big experimental investigation into heredity. 
"The Oxford rivers have had to rest during the last few weeks, because of the pedigree moths. 
These are apparently going on very well indeed. There arc at present about 3500 caterpillars, 
belonging to thirty-eight families forming the third domesticated generation." 
The characters to be dealt with consisted of the number of scales in particular 
colour patches, and the work of counting these was very laborious. A little later 
(16 July, 1899) Weldon writes: 
" The caterpillars are hatchi ng by hundreds and I hope the clean air will help them to do better 
here than in London. From egg to moth, jjoor Warren, in spite of magnificent efforts, had 
a death-rate of over eighty per cent. ; and that seems to me a rather serious thing . . . because one 
cannot be sure that the death-rate was not partly selective with respect to things in the 
caterpillar which are correlated with colour in the moth. The influence of climate is shown by 
the fertility of the eggs — Warren got forty per cent, of fertilised eggs from his pairing and 
an average of over one hundred eggs per batch. Nearly all my pairs lay fertile eggs and those I 
have counted give an average of one hundred and sixty-five eggs per batch." 
And again, on the 14th August of the same year: 
" I want to come and talk to you, especially about death ; but I cannot come till my 
caterpillars are safely turned into pupae. For the sake of these caterpillars I have, at the risk 
of personal liberty and reputation, stolen from the roadside one hundred square feet of clover 
turf, the property of the Lords of various Manors in this neighbourhood. The little rufl&ans 
have now eaten all this clover and for the last day or two of their existence have to be fed 
by hand. — Therefore I have to pluck fresh clover (which is not stealing if you do not do it in an 
enclosed pasture) every day. — My bicycle is nearly worn out from carrying extra weight. Riding 
down a steep hill, with your brake smashed, and with five or six feet of heavy turf on your back 
is like playing at Attwood's machine. You get very near to the theoretical acceleration too ! 
In the course of three years many hundreds of pedigree moths were dealt with 
and the observations were reduced. But no definite inheritance at all of the 
character selected for consideration was discovered. Weldon, I believe, thought 
that there had been some fatal mistake in the selection of pairings, and undoubtedly 
