324 .M ERISTIC VARIATION. [PART I. 



central pad in the pes bore to the digits internal to the axis of sym- 

 metry a relation comparable with that which the chief central pad bears 

 t<> the digits III V, but the secondary central pad is at a higher level 

 than the primary one.] It was especially noted that the details in the 

 arrangement of the pads were inherited in several instances. 



The history of the descendants of the 6-toed cat was followed and 

 a genealogical tree is given shewing that the abnormality has been 

 present in a large proportion of them. This was observed in five 

 generations from the original G-toed cat, so that including the mother 

 of the 6-toed cat the family has contained polydactyle members for 

 seven generations. It may reasonably be assumed that in most of these 

 cases the fathers of these kittens have been normal cats and a good deal 

 of evidence is adduced which makes this likely. 



It was observed also that some normal cats belonging to this family 

 gave birth to polydactyle kittens. In the later period of the life of 

 the original 6-toed cat she gave birth to kittens which were all normal. 



I know no case of reduction in number of digits or of syudac- 

 tylism in the Cat. 



MAN AND APES. 



INCREASE IN NUMBER OF DIGITS. 



Increase in the number of digits occurs in Man in many forms. 

 Among them may be distinguished a large group of cases differing 

 among themselves but capable of being arranged in a progressive 

 series like that described in the Cat. These cases are all examples 

 of amplification or proliferation of parts internal to the index of 

 tin 1 manus. 



Taking the normal as the first Condition, the next in the 

 progress is a hand having the digits II V normal, but the thumb 

 with thivr phalanges, or as the descriptions sometimes say, "like 

 ;in index." (Condition II.) 



In the next condition a two-phalanged digit is present internal 

 to the three-phalanged thumb." (Condition III.) In the next 

 Condition the digit internal to the three-plmlanged "thumb'' has 

 itself three phalanges. (Condition IV.) A variant from this oc- 

 curred in the left hand of a child (No. 488) of parent having hands in 

 ( 'ondition IV. In the child the right hand was in Condition IV, but 

 in the left there were the usual four digits II V, and internal to 

 ih. 'in two complete digits, each of three phalanges, but of these the 

 external had a small rudimentary digit arising from the meta- 

 carpus. Hence the hand may be described as composed of two 

 groups, the one containing four and the other three digits. 



In one case, \... 4IMI, I he ri^lit hand was in Condition IV, but 

 the left hand was advanced further. For in it the metacarpal of 

 the innermost digit bore a 2-phalanged digit internally to its 

 3-phalanged digit. This may be considered as a Condition V. 



