154 HEREDITARY CHARACTERS 



appendages useful to them in the pursuit of their prey, and 

 in escaping their enemies, the parasite frequently consists of 

 very little more than a digestive and a generative apparatus. 

 Every other part of its body has degenerated. On the other 

 hand, races subjected to stringent selection show no signs of 

 degeneration. On the contrary they improve from generation 

 to generation in so far at least as to become more resistant 

 to the unfavourable factors in their environment. If they 

 do not, they disappear. 



It has been claimed that races of men living in slums 

 degenerate. The slum environment is supposed to react un- 

 favourably upon the parents, and this injures their germ cells, 

 so that the offspring are weakly and degenerate. This is 

 supposed to go on from generation to generation, the race 

 subjected to slum environment deteriorating. In this case it 

 must be realised first of all, that just as with Nageli's Alpine 

 plants, the children are subjected to the same external in- 

 fluences during their period of growth, and indeed for their 

 whole lives, as were the parents. Therefore it is obvious 

 that they must tend to make the same acquirements as their 

 parents. With regard to the effect upon the race, a recent 

 Royal Commision has collected and considered the available 

 evidence upon this point. One of the conclusions of the 

 Commision is as follows : " Many races have been exposed 

 to one or other of all the ill conditions which have been 

 alleged as causes of filial deterioration. In every case the 

 only apparent effect has been to render these races capable 

 of dwelling comparatively unharmed under such conditions. 

 It is not to be conceived that a race which deteriorates in 

 every generation can emerge from the struggle not weakened 

 but strengthened. Moreover, almost complete disproof of 

 this hypothesis is furnished by the facts submitted to us by 

 the medical investigators." 1 Of all the existing races in 



1 Report of ike Royal Commission on the Care and Control of the Feeble- 

 minded, p. 184. It was subsequently stated in print that the Royal Com- 

 mission had found evidence to show that degeneration was produced by slum 

 environment. In answer to this, Dr. H. B. Donkin, one of the members of 

 the Commission, wrote as follows to the Westminster Gazette, August 22, 1908 : 



