MENTAL CHARACTERS IX MAN 153 



occipital prominence, and usuall}' in older cases a 

 deeply furrowed tongue. The mentality is nearly 

 always that of a four-year-old child. Mongolians 

 usually appear in good-class families, they are not 

 associated with feeblemindedness, and are frequently 

 the last born in large families. The}' probably result 

 from derangement of function (uterine exhaustion) 

 leading to arrest of development, beginning at a 

 definite point in the prenatal development. The 

 causation of the type according to Goddart {191 4) 

 appears to be purely physiological, without any 

 element of inheritance. Probably defects of certain 

 internal secretions are involved. It has recently been 

 claimed, however, that there is some reason for 

 regarding Mongolianism as a recessive Mendelian trait 

 (see Davenport, 1920). There is evidence also that 

 idiocy frequent!}' results from a severe infection, 

 from cerebro - spinal meningitis, or from S3'philis, 

 alcoholism, or addiction to drugs on the part of 

 the parents. But, according to Davenport (1920), 

 statistics show that the great mass of idiots arise 

 from feebleminded parents. 



The controversy between the schools of Pearson 

 and Davenport turned on the terms in which the 

 inheritance of feeblemindedness is to be stated. 

 Both agree that the condition is inherited. It is 

 possible that the inheritance is not always strictly 

 Mendelian, although it appears to be usually in con- 

 formity with the simple Mendelian scheme. It would 

 appear that occasional departures from strict con- 

 formit}' with the Mendelian scheme may be expected 

 in connection with the inheritance of mental charac- 

 teristics. Nevertheless, it must be remembered that 

 with feeblemindedness, as with other Mendelian 

 characters, the expression of the inheritance may be 

 modified by the presence of other deternuners. It is 

 also possible that the inheritance follows diflferent 



