PHYSICAL CHARACTERS IN MAN 125 



Iron, who died in 1424, and it has been handed clown 

 continuously to the present time, hence for a period 

 of probabh^ more than 500 years, or fifteen to twenty 

 generations. The condition is less marked in the 

 women, and Haecker interprets it as the result of 

 the loss of an inhibitin£>: factor which normally reiiu- 

 lates in Europeans the development of the lower 

 lip and jaw. At least one other sporadic case of 

 prognathism is known to me, but I am not aware 

 of any other data concerning its inheritance. In 

 this case the father has the peculiarity, while one of 

 four children has it in an extreme degree and two 

 others to a less degree. This type of prognathism 

 suggests a mild form of the condition seen in the bull- 

 dog — a mutation which also occurs in cattle, foxes, 

 and other mammals. Donitz (1868), for example, 

 describes a fox skull shaped like a bull-dog's, w^ith 

 a short snout and the mandible turned up in front 

 of the premaxillse. See also Ktihn (1877) and Mivart 

 (1890), where much other information concerning 

 variations in dogs and other Canidae will be found. 



Variations of the type just mentioned we now call 

 parallel mutations (see Gates, 1921, chap, v.), since 

 they result from similar changes in the germ plasm. 

 The list of such cases in mammals, given in Table IV., 

 is taken chiefly from Davenport (191 6), who further 

 points out that rabbits and guinea-pigs both show 

 agouti, yellow, chocolate, black, albino, and other 

 colours. Also the Angora t3^pe of coat is found in 

 rabbits, guinea-pigs, cats, dogs, goats, sheep (Lincoln), 

 and others. 



The medical and anatomical literature on the subject 

 of the inheritance of abnormalities in man is much 

 too extensive to consider here. Only a few cases, 

 where the manner of inheritance through several 

 generations is known, are included. But in a great 

 number of other pathological and anatomical con- 



