228 COOK 



only it be allowed a reasonable diversity of alternatives of ex- 

 pression. But if too closely restricted to the monotonous repe- 

 tition of the same story in each generation it wanders from the 

 hereditary pathway, though it may be recalled to the path by 

 reminiscent contact with another wanderer from the same 

 group. 



It is very natural to infer that the characters of conjugate 

 organisms are contained in the germ-cells, since the organisms 

 are known to develop from germ-cells. But as 3^et we do not 

 know how the characters are contained in the germ-cells. We 

 have no concrete knowledgre whatever of the nature of charac- 

 ters during the interval of transmission or pre-expressional 

 existence. But we do know that the conditions of character- 

 expression are essentially different from those of character- 

 transmission. Dominance and potency are -phenomena of ex- 

 p7-csston, and afford no hint or basis of inference regarding the 

 nature of the 7nechams7n of transmission. 



There is no longer any reason to believe in any general or 

 fundamental difference between somatic and germinal tissues 

 as alleged by Weismann. The bodies of the higher plants and 

 animals simply represent different degrees of vegetative special- 

 ization of tissues once wholly reproductive. A distinction is to 

 be drawn, however, between the transmission of characters by 

 simple or exjugate cells and the expression of characters by 

 conjugate or double-celled structures. Mendelism and other 

 forms of polar descent give us no new knowledge regarding 

 the structure of gametes. They concern only the expression 

 relations which these gametes assume in the conjugate condi- 

 tion. 



Conjugate organisms are not merely resultants of the charac- 

 ters which the gametes were adjusted to bring into expression ; 

 they may show a reciprocal expression of the gamete polarities, 

 or may have characters which neither of the gametes would 

 have expressed if it had a partner of its own kind. If two 

 magnets or magnetic compasses are brought together their 

 directions will change, and if one overpowers the other both 

 may take the same direction. Transmission is represented by 

 the dial of the compass, expression by the needle. One organ- 



