No. 523] INHERITANCE IN POTATOES 



429 



median diameter. The varieties, the length of whose 

 tubers is not over one and one-quarter times the medium 

 diameter, I have called round. Two selfed round varie- 

 ties gave only round progeny. Twelve varieties with oval 

 tubers when selfed gave elongated, oval and round 

 progeny. The ratio of other types to round was about 

 nine to one. Either there is a series of factors for shape 

 with the round type as the final subtraction form, or 

 the oval types are hetorozygotes of elongated and round. 

 The latter interpretation is more likely to be correct, 

 because oval types have been the popular market types 

 for many years and therefore been used as parents in 

 crosses. 



Depth of Eyes 

 Shallow buds or eyes are required for profitable com- 

 mercial varieties, yet from one fifteenth to one fourth 

 of the progeny of ten selfed varieties were deep-eyed 

 forms. Three selfed varieties gave no deep-eyed prog- 

 eny. No progeny of deep-eyed seedlings were obtained, 

 but it seems probable that this character is recessive to 

 shallow eye. 



The writer is fully aware that these few observations 

 do not prove that the characters in which potato varie- 

 ties differ all segregate in Mendelian proportions after 

 crossing. A long series of crosses is necessary to an- 

 alyze correctly the behavior in inheritance of such char- 

 acters as shape. On the other hand, the color characters 

 in stem, blossom and tuber are definite and discontinu- 

 ous, and are alternative in inheritance. The chaotic ap- 

 pearance of the progeny of our commercial potatoes is 

 only apparent. They readily fall into a simple classi- 

 fication and their exact behavior in inheritance could 

 be readily determined if it were not for the difficulties 

 attending successful crossing. 



As the writer has previously stated, 3 certain char- 

 acters pair with their own absence in crossing and these 



""The Transmission of Variations in the Potato in Asexual Reproduc- 



