EFFECTS OF AMPHIMIXIS ON ONTOGENY 283 



dominated at the formation of the brain, which likewise arises 

 from the external germinal layer, for the person in question 

 resembles his mother as regards most of the mental qualities, 

 such as intelligence, talents, and strength of will. This can 

 only be accounted for on the supposition that the determinants 

 of the subsequent descendants of the primary ectoderm-cell were 

 unable to exert any influence upoji this cell itself; in it they 

 were still latent, and in this condition were merely passed on to 

 succeeding cells. If the ids of subsequent generations of these 

 primary ectoderm-cells which formed the rudiments of the brain, 

 contained more maternal than paternal homodynamous deter- 

 minants, a resemblance to the mother instead of to the father 

 would arise at this point. 



In the above case, the entire brain does not seem to have 

 taken after that of the mother, for marked paternal traits also 

 exist in it. According to our theory, it may well be conceived 

 that even such a repeated alternation of hereditary tendencies as 

 has occurred in this instance is predetermined in the germ, for 

 the power of the paternal, and naturally also of the maternal ids, 

 varies throughout ontogeny at every further stage in the division 

 of the ids, and the relation between the controlling forces of the 

 father and mother may be transposed. In general we might 

 even expect that one or other group would predominate in most 

 cases, and that the child is consequently composed of a com- 

 bination of parental characters which varies in different parts. 

 The parts or organs which resemble those of the same parent 

 may also vary very considerably as regards size : this is 

 possibly true of a single cell, as well as of a whole organ or an 

 entire germinal layer, or even of the entire organism. 



This theoretical deduction is in general supported by facts, 

 for a child is rarely or never an exact repetition of either parent. 

 It is by no means easy, indeed, to form a correct estimate with 

 regard to the resemblance between parent and child, for in order 

 to do so, an exact knowledge of both at the same ages would be 

 necessary, and a detailed comparison is only possible between 

 father and son, or mother and daughter. It would therefore 

 be essential to compare photographs of the father and son, at 

 the same ages ; and this, as far as my knowledge of the observa- 

 tions which have been made on heredity extend, has never yet 

 been done. It would, moreover, be necessary to photograph 

 the whole bodv, and not merelv the face. 



