266 THE AMEBIC AX XATUEALIST [Vol. XLVI 



The question arises as a result of the somewhat con- 

 flicting evidence as to the crossing of brachycephals and 

 dolichocephals in man, what happens when we cross two 

 phyla of lower mammals which have been diverging along 

 separate allometric lines and in the meantime have ac- 

 quired a greater or less number of new characters which 

 when sufficiently developed attain specific rank. 



The answer is given very distinctly in the cross between 

 the dolichocephalic horse (E. cab alius) and the meso- 

 cephalic ass {E. asinus). Here we learn again that pro- 

 found differences have been established through con- 

 tinuity and that we are enabled to split up these differ- 

 ences into distinct or partially blending units through 

 cross breeding. 



5. Blended or Alternating Heredity in Horses. 37 

 So high an authority as J. Cossar Ewart (1903) has 

 sustained the prevailing view that in the mule there is 

 generally an imperfect blending of the characters of the 

 immediate parents ; the same author, however, notes that 

 mules occasionally serve as examples of unit or exclusive 

 inheritance. 38 He cites two cases: (1) a mule out of a 

 well-bred, flea-bitten New Forest pony closely resembles 

 her sire, the ass; (2) a "calico" mule, on the other hand, 

 is surprisingly like his dam, an Indian "painted" pony. 

 This painted mule demonstrates that the ass is not always 

 more prepotent than the horse. From this author's very 

 extensive breeding experiments the following conclusions 

 are reached: the less fixed or racially valuable characters 



