" Natural Selection " 51 



blindness, which has been recorded, through the males 

 only, of seven generations, (b) similarly, cataracts in the 

 males of four generations, (c) " Edward Lambert, 

 born 1717, is said to have been born covered with 

 spines. In his children this abnormality persisted for 

 five generations, and in the males only ; this pecu- 

 liarity began to be manifest from the sixth to the ninth 

 month after birth." Now, it must be evident to 

 everyone that these abnormal qualities never persist : 

 in other words, there is a return to the average through 

 the potent influence of marriage, just as in eight 

 generations all trace of the negro can be eliminated by 

 constant inter-marriage with the white. These 

 instances give additional support to Darwin's own 

 dictum that " isolated sports must be swamped by 

 continual crossing of the normal type." 



On page 347 Messrs. Dewar and Finn deal with the 

 " struggle for existence." Their remarks are so novel in 

 any present-day work on Zoology, that I feel impelled 

 to quote the passage in extenso : " As usual, Darwin's 

 disciples have failed to improve upon the accounts he 

 gave of the nature of the struggle for existence. This 

 is set forth in Chapter III of the ' Origin of Species.' 



" 'The causes,' writes Darwin (new edition, p. 83), 

 ' which check the natural tendency of each species 

 to increase in number are most obscure. Look at the 

 most vigorous species ; by as much as it swarms in 

 numbers, by so much will it tend to increase still 

 further. We know not exactly what the checks are, 

 even in a single instance.' This is perfectly true," say 

 Dewar and Finn, " nevertheless, elaborate theories of 

 protective and warning coloration and mimicry have 

 been built up on the tacit assumption that the checks 

 to the multiplication of all, or nearly all, species are the 

 creatures which prey upon them. Possibly no Wal- 

 laceian asserts this in so many words, but it is a 



