238 HEREDITARY TRANSMISSION [CH. 



M y with the result that "female intersexes" (combining the 

 characters of both sexes) are produced. He further finds 

 that the potency of M behaves as a Mendelian character, 

 but that the potency of F is transmitted only by the 

 female, and remains constant in all descendants in the female 

 line. From this he infers that F is a cytoplasmic factor, 

 borne by the egg and not by the spermatozoon. 



A very nearly related question is the precise meaning 

 to be attached to the statement that "the factors for sex 

 or for Mendelian characters are borne by chromosomes." 

 Evidence will be given in the following chapter that the 

 cytoplasm is not without influence in the development of 

 inherited characters, and this fact has been held to disprove 

 the chromosome hypothesis. But a chromosome can ob- 

 viously act only in its relation with the cytoplasm, and if 

 the cytoplasm is altered this relation must evidently change 

 with it. When, therefore, it is said that chromosomes bear 

 the factors for characters it is implied that these factors 

 are in relation with the cytoplasm, and will only produce 

 their effects if that relation exists. A simple chemical ana- 

 logy may make the conception clearer. If in the hydro- 

 carbon CH 3 H the fourth hydrogen atom is replaced by 

 chlorine (CH 3 C1) or by hydroxyl (CH 3 OH), substances of 

 very different properties are produced. A quite parallel 

 series is represented by the compounds C 2 H 5 H, C 2 H 5 C1, 

 C 2 H 5 OH, and although the two series of substances are not 

 identical, it is perfectly correct to say that the change from 

 a hydrocarbon to a chloride or an alcohol is due to the 

 substitution of a hydrogen atom by one of chlorine or by 

 the hydroxyl radicle. The cytoplasm, in this analogy, is 

 represented by the hydrocarbon radicles, CH 3 ,C 2 H 5 and 

 so forth, and the effects on the general nature of the result- 

 ing compound of substituting Cl or OH for the H 



