No. 523] INHERITANCE IN POTATOES 



425 



tion of plants, together with the characters possessed 

 by their parents. I have endeavored to find what char- 

 acters were possessed by the parents of the varieties used 

 in crossing but have found no trustworthy data. The fol- 

 lowing conclusions, therefore, are tentative. Nothing is 

 known about the behavior of the characters when ex- 

 tracted. The data show that certain characters segre- 

 gate, they give some evidence as to dominance and re- 

 cessiveness, but they do not show the exact behavior of 

 the Mendelian factors concerned, under different com- 

 binations. 



Color in the Plant Stem 



Many varieties have a purple anthocyan sap color 

 which gives the plant stem a dark appearance quite dis- 

 tinct from the clear green stems of the varieties in 

 which it is absent. The color is variable in amount in 

 different varieties. In some it extends throughout the 

 petioles and petiolules; in others it can only be detected 

 on the stems of the young seedling. My counts were 

 made on seedlings about four incites high. 



The color is evidently of the same nature as that 

 found in many other cultivated plants. Its widespread 

 occurrence and seeming nselessness in the plant's 

 economy would place it in the category of typical varie- 

 tal characters in the sense used by De Vries. It forms 

 a single allelomorphic pair with its absence. 



One purple- stemmed variety selfed gave all purple- 

 stemmed progeny. Four purple varieties selfed, each 

 showed segregation into two distinct classes, purple and 

 non-purple. Fifty-four purple plants and seventeen 

 non-purple plants were obtained. (These figures as well 

 as those that follow are the records saved from the fire.) 

 In each of these cases we may take it that the parent 

 plants were heterozygous for the purple color, and ap- 

 proximated the simple three to one Mendelian ratio when 

 self-pollinated. Four green-stemmed varieties were 



