THE FACTORIAL. HYPOTHESIS 215 



be nothing but a condition produced by the factor 

 which ordinarily makes the fully purple flower, quanti- 

 tatively diminished. The pied animal, such as the 

 Dutch rabbit, must similarly be regarded as the re- 

 sult of partial defect of the chromogen from which the 

 pigment is formed, or conceivably of the factor which 

 effects its oxidation. On such lines I think we may 

 with great confidence interpret all those intergrading 

 forms which breed true and are not produced by 

 factorial interference. 



"It is to be inferred that these fractional degrada- 

 tions are the consequences of irregularities in segrega- 

 tion. We constantly see irregularities in the ordinary 

 meristic processes, and in the distribution of somatic 

 differentiation. We are familiar with half seg- 

 ments, with imperfect twinning, with leaves partially 

 petaloid, with petals partially sepaloid. All these 

 are evidences of departures from the normal regu- 

 larity in the rhythms of repetition, or in those waves 

 of differentiation by which the qualities are sorted 

 out among the parts of the body. Similarly, when 

 in segregation the qualities are sorted out among the 

 germ cells in certain critical cell divisions we can not 

 expect these differentiating divisions to be exempt 

 from the imperfections and irregularities which are 

 found in all the grosser divisions that we can observe." 



Bateson has assumed because the character ap- 

 pears to fractionate that we are to infer that some 

 particular factor, that stands for it, fractionates too, 

 but such a conclusion overlooks the fact that a char- 

 acter is produced by many factors in co-operation, 



