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THE AMERICAN NATURALIST [Vol. XLV 



duced offspring of both sexes. Post-mortem dissection of the two 

 females showed that the operation of removing an ovary had 

 been entirely successful, and new ovarian tissue had not been 

 regenerated. These results disprove the theory so far as concerns 

 these animals. 



In the March number of the Zeitschrift fiir Induktive Abstam- 

 mungs- und Vererbungslehre Dr. Gates presents a very interest- 

 ing paper on the inheritance of pigmentation in Oenothera. He 

 shows that some quantitative variations in the pigmentation of 

 the calyx of O. ruhrinrrris are not hereditary, while other quan- 

 titative variations are hereditary. One striking case of a mutant 

 which produces an increased amount of anthocvanin was found 

 in his investigations. 



To most students of genetics the most interesting part of Dr. 

 Gates's paper will he his discussion on pages 367-8 of the prob- 

 able nature of the differences between genotypes which furnish 

 us our Mendelian character pairs. The evidence he presents is 

 strongly against the assumption that all of these hereditary dif- 

 ferences are due to the loss or origination of definite cell organs 

 which can be looked upon as the physical basis of the separately 

 heritable characters. Rather, "Everything points to its being 

 what it appears to be, namely, a positive variation in some 

 physiological factor concerned in anthocvanin formation. It is 

 not necessary to think of a form as having lost an inhibitor, but 

 rather has there been a quantitative readjustment of the relation 

 between the substances which by their chemical interactions pro- 

 duce anthocvanin, and those which decompose it as soon as 

 formed, or which by their presence divert the metabolic processes 

 and bring about chemical reactions of a different sort." 



He states that the appearance and behavior of the mutant 

 above referred to (0. rubricalyx) can not be explained on the 

 basis of the presence or absence of any factor or substance in this 

 mutant which is not also present in 0. rubrinerris. "Obviously 

 the germinal change has been rather in a quantitative readjust- 

 ment, and it would seem that many, though not necessarily all. 

 the cases of Mendelian color inheritance "are explainable on a 



hypothesis." * ^ ^ * ' a ? 



He calls attention to the well-known fact that, especially in 

 organic chemistry, many reactions may go in quite different 

 directions according to the relative amounts of the reacting sub- 

 stances present, and suggests that many of the phenomena of 



