688 THE AMERICAN NATURALIST [Vol. XL VII 



at pleasure for comparisons. The distinction between 

 A and C or B and C allows of practically no difference of 

 opinion. Personal equation probably plays considerable 

 part in distributing the seedlings between those which 

 germinated normally and those which were somewhat 

 abnormal, for there is no clear line of distinction between 

 the two. Practically all the cases were decided by myself. 

 The abnormalities were in small part teratological and in 

 part physiological or pathological — i. e., curved hypo- 

 cotyls failing to bring the plumule promptly to the sur- 

 face, cotyledons failing to free themselves from the 

 seed coat, blighted primordial leaves, etc. The results 

 of this study seem to indicate the need of more precise 

 consideration of aberrant seedling in future experiments. 



III. Materials 



This research and the one which preceded it are in- 

 between seed weight and seed mortality in Phaseolus 

 vulgaris as a whole, 8 and at the same time lay up data 

 which when sufficient ly supplemented by others of various 

 kinds shall enable one to determine whether (and if so, 

 why) the relationship between seed weight and seed 

 mortality differs from variety to variety, or whether it 

 is dependent upon the conditions under which the seeds 

 planted were grown or those under which they were 

 germinated, or upon the age of the seeds. 



Five characteristics were, therefore, deemed desirable 

 in the seeds used, (a) They should be known from 

 breeding tests to belong to strains as uniform as possible. 

 (b) They should represent several distinct varieties, (c) 

 Different lots should have been grown under as diverse 

 environmental conditions as possible, (d) Different ages 

 of as nearly as possible comparable seed should be inves- 

 tigated, (e) Comparison with the results of field experi- 

 ments should be easily carried out. 



