746 THE AMERICAN NATURALIST [Vol. XLIV 



velopment may be subjected to very different weather 

 conditions. This is of so much importance in maize, for 

 instance, that I am now beginning a study of size in- 

 heritance of crosses between parents differing greatly 

 in size but only slightly in oarliness. 



There may possibly be definite correlations between 

 different dimensions, as length and breadth of the same 

 plant part. That is to say, shapes may be definitely in- 

 herited. Observations on F 2 bean seeds where the par- 

 ents differ in size but not in shape indicate that length 

 and breadth are probably not inherited independently 

 of each other. Large round beans crossed with small 

 round ones do not give any long slender beans in F 2 but 

 only large, medium and small, round ones. On the other 

 hand, when the parents differ in shape as well as in size, 

 intermediate and parental shapes as well as intermediate 

 and parental dimensions occur in F 2 . 



In short, the inheritance of sizes and shapes is not the 

 simple matter that the inheritance of, say, color is — and 

 recent developments indicate that color inheritance is 

 not always a simple three-to-one affair. It is certainly 

 well that most effort has first been directed to a solution 

 of some of the more simple problems of genetics. With- 

 out a knowledge of the later studies in color inheritance, 

 one could scarcely hope to get far in the investigation of 

 the inheritance of dimensions, weights and shapes, to 

 say nothing of such questions as whether * ' yield Men- 

 delizes," which some are impatient to have answered at 

 once. 



It has been the purpose of this paper to present a few 

 facts and to suggest many problems with the hope that 

 the attention of other students of genetics will be di- 

 rected to an interesting and important field not much 

 worked as yet. 



