HARRIS AND AVERY: MORPHOLOGICAL VARIATIONS 111 
For the onerous preliminary examination of nearly a half a 
million seedlings we are greatly indebted to Miss Edna K. Lock- 
wood, Miss Margaret Gavin and especially to Miss Lillie Gavin. 
PRESENTATION AND ANALYSIS OF DATA 
The slightest abnormality which we have been able to discover 
occurring in considerable numbers of bean seedlings is the vertical 
separation of the two normally opposite cotyledons. So imper- 
‘ceptible is the line of transition between normal and abnormal that 
personal equation must play some part in classification. The 
cotyledons may be much more widely separated. The variation 
is a purely graduated one, with no sharp lines of demarcation be- 
tween the different degrees of separation. Generally we have 
recognized three grades, but because of the rarity of plants with 
more widely separated cotyledons we have in this paper grouped 
our data into two classes only. The first comprises plants with 
cotyledons 2-3 mm. apart. The second includes all those in which 
they are more distant. 
The number as well as the position of the cotyledons may vary. 
Plants with three instead of two cotyledons fall into two groups; 
those with the normal pair of primordial leaves and those with a 
whorl of three leaves. The latter are by far the more abundant. 
Abnormality developed subsequently to the selection of the 
seedlings in the preliminary sorting may affect either the inter- 
node between the second and the third nodes, that is, between the 
primordial leaf whorl and the point of insertion of the first com- 
pound leaf or leaf whorl, or it may be confined to the number or 
structure (or number and structure) of the leaves inserted at the 
third node. 
In the original selection of individuals abnormal in the char- 
acters of the first or second node, only those with sensibly normal 
axes (hypocotyl and epicotyl) were chosen for the purposes of the 
present study. 
Two types of abnormality in the axis beyond the second (the 
primordial) node have been considered. 
The first is a sensible broadening of the axis, identical with or 
similar to fasciation. This is a graduated character. The line of 
demarcation between normal and abnormal is not clearly marked. 
