670 



THE AMERICAN NATURALIST [Vol. XLVI 



Considering now the weight of the seeds produced by 

 the comparison plants, we note that of the 28 differences 

 which may be taken (within and between strains) be- 

 tween plants of luxuriant and those of depauperate an- 

 cestry, 15 are negative and 13 are positive in sign, a devi- 

 ation of only 1 ± 1.79 from the expected 14: 14 ratio. 



Of the individual differences, the largest is .023 gram, 

 while most of them fall, towards zero. Averaging we 

 get: 



Positive Differences, + -00915 gr. 

 Negative Differences, —.00831 gr. 

 All Differences, —.00020 gr. 



Surely values as low as this can not give much weight to 

 the assertion that depauperization of the parents has 

 had any influence upon the weight of the seed of the off- 

 spring plants. 



Looked at in a preliminary and superficial way (and 

 it hardly seems worth while to go into the matter more 

 minutely until other data are tabled and reduced), the 

 data seem to indicate that the weight of the seed is a 

 character much less directly dependent upon cultural 

 conditions than are the vegetative characters of the 

 plant. Conditions which reduce these latter may not 

 materially affect seed weight. 



Possibly, the environmental complexes available were 

 such as to affect certain characteristics of the ancestral 

 plants, while leaving others, i. e., seed weight, unmodi- 

 fied. Possibly, seed weight is a character little affected 

 by external conditions of any kind. These are questions 

 which can only be solved by further experiments de- 

 signed to determine whether some environmental com- 

 plexes regularly affect seed weight while others do not, 

 and to ascertain what influence, if any, such reduction 

 has upon the characteristics of offspring seeds. 



E. Combination Characters 

 Some characteristics are combinations of two or more 

 individual measurements. Such are, for example, the 



