VI.] THEIR SIGNIFICANCE IN HEREDITY. 365 



generally also in motile power, must contain the same funda- 

 mental substance, the same idioplasm. Otherwise the female 

 germ-cell could not transmit the male characters of the 

 ancestors of the female quite as readily as the female characters, 

 nor could the male germ-cell transmit the female quite as 

 readily as the male characters of the ancestors of the male. 

 It is therefore clear that the nuclear substance itself is not 

 sexually differentiated. 



I have already previously pointed out that the above-mentioned 

 facts of heredity contain the disproof of Minot's theory, inas- 

 much as the egg-cell transmits male as well as female characters. 

 Strasburger^ has also raised a similar objection. I consider 

 this objection to be quite conclusive, for there does not seem 

 to be any way in which the difficulty can be met by the 

 supporters of the theory. The difficulty could indeed be 

 evaded until we came to know that the essential part of the 

 polar body is nuclear substance, and that the latter must be 

 regarded as idioplasm, — as the substance which is the bearer 

 of heredity. It might have been maintained that the male part, 

 removed from the ^%%i consists only in a condition, perhaps 

 comparable to positive or negative electricity ; and that this 

 condition is present in the substance of the polar body, so that 

 the removal of the latter would merely signify a removal of the 

 unknown condition. I do not mean to impl}^ that any of those 

 who have adopted Minot's theory have had any such vague 

 ideas concerning this process, but even if any one were ready 

 to adopt it, he would be unable to make any use of the idea. 

 He would not be able to support the theory in this way, for we 

 now know that nuclear substance is removed with the polar 

 body, and this fact requires an explanation which cannot be 

 afforded by the theory, if we are right in believing that the 

 expelled nuclear substance is not merely the indifferent bearer 

 of the unknown principle of the male condition, but hereditary 

 substance. I therefore believe that Minot's, Balfour's, and van 

 Beneden's hypothesis, although an ingenious attempt which 

 was quite justified at the time when it originated, must be 

 finally abandoned. 



1 Strasburger, ' Neue Untersuchungcn iibcr den Bcfruchtuiigsvorgang: 

 bei den Phanerogamen als Grundlage eincr Theoric der Zcugung." 

 Jena, 1884. 



