406 



BULLETIN No. 127. 



[August. 



a definite relation between the shape of tubers, and starch content 

 and power to yield, and that such individual characters were in a 

 great measure transmitted. The author believed that he was war- 

 ranted in concluding that within a variety and under like conditions, 

 flat-round tubers produce those richest in starch, but weakest in 

 yielding power, while cylindrical-oblong tubers give a progeny poor 

 in starch content but of greater yield. The explanation of the cor- 

 relation between starch content and flat-round shape is from the 

 following facts. The zone of highest content (see discussion con- 

 cerning quality) in the potato lies next to the outside of the tuber. 

 Other things being equal then, the tuber having the largest propor- 

 tion of outer starch zone is the richest in starch. This is satisfied 

 by the flat-round tuber. 



In these investigations two varieties were used and selections 

 made of rather small-flat-round tubers on one hand, and large- 

 cylindrical-long tubers on the other. The former showed a specific 

 gravity of more than i.n and the latter less than i.io. These 

 specific gravities correspond in Maercker's tables to more than 20 

 percent of starch in the former and less than 18 percent in the 

 latter. 



The results were as follows : 



