NOTES AND LITERATURE 



NOTES ON HEREDITY 



Miss Wiieldai.e presents an interesting theory concerning the 

 formation of anthocyanin. 1 The theory for which a good deal 

 of evidence is presented is that of the reversible reaction 



Glucoside -f water = chromogen -j- sugar, 



which is controlled by one or more enzymes. 



Whether this reaction shall go forward or backward depends 

 upon the relative amount present of the various substances enter- 

 ing it and upon the nature and quantity of the enzymes which 

 bring about the reaction. She points out that certain species 

 having flowers, leaves, etc., slightly or not at all colored give rise 

 to colored varieties which are recessive to the type. These facts 

 are explained if we assume that the colored forms arise because 

 of the absence in the color tissue of the enzyme which causes the 

 synthesis of the glucoside. Under these conditions, chromogen 

 which is formed would be free and available for oxidation into 

 pigment. In the type the enzyme is supposed to be present, and 

 the condition of equilibrium is such that all, or nearly all, of the 

 chromogen unites with sugar and hence can not be oxidized. 



In the Journal of Morphology for March, 1911, Wilson gives a 

 very interesting discussion of the chromosome behavior in Xezara, 

 following which he gives a discussion of the possible ways in 

 which the idiochromosomes may be changed in number. 



One of the most interesting things in this paper to the student 

 of genetics is the high degree of probability which Wilson shows 

 to exist that the behavior of the idiochromosomes is not only 

 accountable for sex inheritance, but for the inheritance of certain 

 sex-limited characters. He points out that cytological considera- 

 tions render it probable that the morphological dimorphism of 

 the spermatozoa in certain species has arisen by the transforma- 

 tion of a single pair of chromosomes, producing an XY pair. He 

 also shows that in certain species the XY pair of chromosomes 



