110 HARRIS AND AVERY: MORPHOLOGICAL VARIATIONS 



node in the case of plants showing various structural abnormalit \ 

 at the first two nodes. 



Phaseolus is well suited for such investigations. The norrl 

 seedling has two cotyledons, inserted at the same level, and ti 

 opposite primordial leaves. A large number of structural vai- 

 tions, four types of which will be considered in this paper, ii 

 occur. The chief disadvantage lies in the rarity of many of \ 

 variations in the lines with which we have dealt. The securing 

 adequate series is excessively laborious. The present paper; 

 based upon a careful study of the variations in the first three no 

 of 16,348 plants, which were selected from about 450,000 seedli s 

 examined for the characters of the first and second node. 



When in the following paragraphs we refer to normal &amp;lt;1 

 abnormal plants or seedlings, it must be understood that 1; 

 applies to the characteristics of the individual as determined i 

 the basis of the first two nodes, the cotyledonary and the ]- 

 mordial only. In its later development the &quot;abnormal&quot; pit 

 may remain &quot;abnormal&quot; or become &quot;normal,&quot; and the &quot;norm 

 plant may either continue to be &quot;normal&quot; or become &quot;abnorm; 



The nature and method of classification of the abnormal! s 

 dealt with will be discussed in the presentation of the data belov 



MATERIALS AND METHODS 



The materials upon which this study is based are a series f 

 lines of White Navy beans grown at the Station for Experimei .1 

 Evolution during the past several years. The seeds were ! 

 vested from field cultures in 1915 and germinated in sand in e 

 autumn of 1916. 



Seedlings which were abnormal in the characters of the 1-t 

 or second node, i. e., in the number or insertion of the cotyled s 

 or of the primordial leaves, were sorted out for potting in soil d 

 subsequent study of the third node, that normally giving ris&amp;lt; o 

 the first compound leaf. 



For each abnormal individual, a normal control seedling fin 

 the same parent plant was taken at random to serve as a basi &amp;gt;i 

 comparison. Both were potted in soil and grown to a stage \v :i 

 the characteristics of the third node could be accurately de - 

 mined. 



