458 



INHERITANCE. 



Chap. XII. 



Struthers gives the following instance : in the first generation an 

 additional digit appeared on one hand; in the second, on both 

 hands ; in the third, three brothers had both hands, and one of the 

 brothers a foot affected ; and in the fourth generation all four limbs 

 were affected. Yet we must not over-estimate the force of inherit- 

 ance. Dr. Struthers asserts that cases of non-inheritance and of the 

 first appearance of additional digits in unaffected families are much 

 more frequent than cases of inheritance. Many other deviations of 

 structure, of a nature almost as anomalous as supernumerary digits, 

 such as deficient phalanges, 29 thickened joints, crooked fingers, &c, 

 are, in like manner, strongly inherited, and are equally subject to 

 intermission, together with reversion, though in such cases there 

 is no reason to suppose that both parents had been similarly 

 affected. 30 



Additional digits have been observed in negroes as well as in 

 other races of man, and in several of the lower animals, and have 

 been inherited. Six toes have been described on the hind feet of the 

 newt (Salamandra cristata), and are said to have occurred with the 

 frog. It deserves notice, that the six- toed newt, though adult, 

 preserved some of its larval characters; for part of the hyoidal 

 apparatus, which is properly absorbed during the act of metamor- 

 ]3hosis, was retained. It is also remarkable that in the case of man 

 various structures in an embryonic or arrested state of development, 

 such as a cleft-palate, bifid uterus, &c, are often accompanied by 

 polydactylism. 31 Six toes on the hinder feet are known to have 

 been inherited for three generations of cats. In several breeds of 

 the fowl the hinder toe is double, and is generally transmitted 

 truly, as is well shown when Dorkings are crossed with common 



29 Dr. J. W. Ogle gives a case of 

 the inheritance of deficient phalanges 

 during four generations. He adds 

 references to various recent papers on 

 inheritance, ' Brit, and For. Med.- 

 Chirurg. Review,' Ap. 1872. 



30 For these several statements, see 

 Dr. Struthers, ' Edinburgh New Phil. 

 Journal,' July, 1863, especially on 

 intermissions in the line of descent. 

 Prof. Huxley, • Lectures on our Know- 

 ledge of Organic Nature,' 1883, p. 

 97. With respect to inheritance, see 

 Dr. Prosper Lucas, ' L'Heredite Nat.,' 

 torn. i. p. 325. Isid. Geoffrey, ' Anom.,' 

 torn. i. p. 701. Sir A. Carlisle, in 

 'Phil. Transact.,' 1814, p. 94. A. 

 Walker, on ' Intermarriage,' 1838, 

 p. 140, gives a case of five genera- 

 tions ; as does Mr. Sedgwick, in ' Brit, 

 and Foreign Medico-Chirurg. Review,' 



April, 1863, p. 462. On the inheri- 

 tance of other anomalies in the ex- 

 tremities, see Dr. H. Dobell, in vol. 

 xl vi. of ' Medico-Chirurg.Transactions,' 

 1863 ; also Mr. Sedgwick, in op. cit., 

 April, 1863, p. 460. With respect to 

 additional digits in the negro, see 

 Prichard, ' Physical History of Man- 

 kind.' Dr. Dieffenbaeh ('Jour. Royal 

 Geograph. Soc.,' 1841, p. 208) says 

 this anomaly is not uncommon with 

 the Polynesians of the Chatham 

 Islands ; and I have heard of several 

 cases with Hindus and Arabs. 



31 Meckel and Isid G. St. Hilaire 

 insist on this fact. See, also M. A. 

 Roujou, ' Sur quelques Analogies du 

 Type Humain,' p. 61 ; published, I 

 believe, in the ' Journal of the Anthro- 

 polog. Soc. of Paris,' Jan. 1872. 



