

16 



INHERITANCE. 



Chap. XII. 



water fish are cut off, they are perfectly reproduced in about six week 



time. 



s 



dig 



om these several facts we may infer that supernumerary 



bryonic condi- 



man 



and that they resemble in this respect the 



di 



and limbs 



lower vertebrate 



G 



They also resemble 



fin 



digits of some of the lower animals in the number exceeding 



mammal, bird, existing reptile, or amphibian 



the tubercle 



the hind feet of 



toad and other tailless 



than fin 



h 



Batrachians be viewed as a digit) has more 



fishes sometimes have in their pectoral fins as many as twentv 



metacarpal and phalangeal bones, which, together with the bony 



filaments, apparently represent our dig- 



So 



again, in certain 



ptiles, namely, the Ichthyopteryg 



" the digits may be seven, eight, or nine in number, a significant 

 mark," says Professor Owen, " of piscine affinity." 39 



We encounter much difficulty in attempting to reduce these 

 various facts to any rule or law. 



The 



the additional dig 

 inner or outer nn 

 be traced from a 



s — their irreguh 

 gin of the band 



to 



ruber of 

 ther the 



gradation 



h 



mer 



loose rudiment of a sin sde dis- 

 ci & 



pletely double hand — the occasional appear 



of 



tional dig 

 tated — the 



m 



the 



am 



after 



limb has bee 



facts appear to indicate mere fluctuating 



monstrosity; and this perhaps is all 



can, be safely said 



Nevertheless, as supernumerary digits in the bigher animals, fr 



their pow 



of 



rowth and from 



g five, partake of the 



le number thus acquired 

 of the digits in the lower 



vertebrate animals; — as they occur by no means rarely, and 

 transmitted with remarkable strength, though perhaps not n 



ly than some other anom 



d as with animals 



which have fewer than five digits, when an additional one 



ppeai 



s it 



rudiment 

 actual ru 



rally due to the development of a visible 

 s led in all cases to suspect, that, although no 

 m be detected, yet that a latent tendency to 



formation of an additional digit exists in all 



t> 



luding 



On this view, as we shall more plainly 



39 ' On the Anatomy of Vertebrates,' 1866, p. 170 : with respect to the pectoral 

 fins of fishes, pp. 166-168. 



IS 



fo; 



183: 



41 



