Recent Advances in the Study of Heredity. 165 
with it, and one of the handful of men who were on the right 
track, who was unknown to biologists during his life-time. I refer 
to the correspondence between Nageli and Mendel. Mendel first 
wrote to Nageli with the object of procuring specimens of 
Hieracium : he sent him his paper and discussed fully the criticisms 
which Nageli offered. If further evidence were needed that 
Mendel spared no pains in his attempt to explain his theory to 
Nageli, it is to be found in the fact that he went to the 
trouble of putting up packets of peas illustrating his various 
gametic types, and sent them to Nageli. 
Now Nageli was especially interested in the problems pre¬ 
sented by heredity ; but his attitude to it was almost identical with 
that of Charles Darwin. Was it to be wondered at then that he com¬ 
pletely failed to understand the significance of Mendel’s work ? 
Such was the case; for when in 1884 he published his great treatise 
on heredity, 1 no reference was made to Mendel or his work. “ That 
this neglect was due to want of comprehension ” (I quote from 
Bateson’s ‘Mendel’s Principles,’ p. 55) “is evident from a passage 
where he describes an experiment or observation on cats, which as 
it happens gives a simple Mendelian result. The Angora character 
(recessive) disappeared in a cross with a certain common cat whose 
hair character is, as we know now, dominant. The cross-breds 
were mated together and the Angora character reappeared in one 
individual among a litter of common cats. This typically Mendelian 
fact was actually thus under Nageli’s own observation, but from the 
discussion which he devotes to the occurrence it is clear that 
Mendel’s work must have wholly passed from his memory, having 
probably been dismissed as something too fanciful for serious 
consideration.” 
It will be gathered from what I have already said that the 
explanation which I should offer of Nageli’s inability to understand 
Mendel’s work is that the two men were extreme representatives 
of the two diametrically opposite attitudes to the phenomenon of 
inheritance, on which I have already laid stress. Nageli could not 
accept or understand Mendel’s theory without recognizing that the 
problem to whose solution he had devoted so much of his life was 
an unreal one. How unreal the problem, as approached from 
Nageli’s and Charles Darwin’s standpoint, appeared to Mendel can 
be gathered from the fact that so unconsciously certain was Mendel 
of the modern view that he does not stop to consider the opposite 
i Mechanisch-physiologische Theorie der Abstammungslehre. 
