164 MUTATION 



win cites cases of characteristics that he believes 

 to have arisen suddenly, such as the blackness of 

 the japanned peacock, jaw appendages of pigs, 

 short upper jaw and homlessness in cattle, short- 

 leggedness in sheep and dogs, elongated wool in 

 merinos, and downless fruit in peaches. These 

 instances sufficiently indicate Darwin's recogni- 

 tion of saltation, and if he was led to reject it as 

 the usual mode of modification of species, he did 

 so because the doctrine had a crude form and car- 

 ried with it the connotation of something terato- 

 logical or pathological. But is there sufficient 

 evidence that, in rejecting saltation, he regarded 

 evolutionary changes in unit characters to pro- 

 ceed always by the fourth place of decimals? 

 On the contrary, his examples of variations are 

 very unlike the raw material of the biometric 

 school. This is a sample of his idea of variation 

 in poultry: — 



" The tarsi are often feathered. The feet in many 

 breeds are furnished with additional toes. Golden 

 spangled Polish fowls are said to have the skin between 

 the toes well developed." 



In the short section labeled " Remarkable va- 

 riations of Goats," Darwin refers to the great 

 ears of goats of the Island of Mauritius, to the 

 various forms of mammae, to throat appendages, 

 hornlessness, and presence or absence of toe 

 glands. The entire work on Variation under 

 Domestication demonstrates that Darwin fre- 

 quently, if not usually, meant by Variation the 



