Trifoliujii Prate use Oiiiiiqiicfoliiuii. 47 



with more than seven leaflets have never, or only ex- 

 tremely rarely, been produced. As a matter of fact a 

 duplication of the leaves by splitting, which is so common 

 among other plants,^ occurs in my race also, and if it 

 aft'ects a pentamerous leaf, makes a 10-merous one of it. 

 But that is the expression of another latent character 

 which we are not concerned with here. Apart from 

 these I have not yet found in my cultures, in spite of the 

 most careful search, a single instance of a leaf with 

 more than 7 leaflets. 



The character of my race is the quinque foliate leaf 

 which is usually in tlie majority ; the remaining types are 

 grouped round it in accordance with Quetelet's law, so 

 far as the tendency to symmetry permits this. For it is 

 clear that this tendencv does not favor the remilaritv of 

 the curve of variation. The increase in the number of 

 leaflets from 3 to 4 takes place by the lateral splitting 

 of one of the lateral leaflets (see Fig. 3 A), one of the 

 lateral veins becoming the primary vein of the new leaflet. 

 Transitions such as that figured are certainly fairly rare, 

 l)ut all degrees of them, down to a splitting of the small 

 partial stalk of the leaflet, occur from time to time. If 

 only one leaflet is split, the leaf becomes asymmetrical ; 

 but if the two lateral leaflets split, the whole may remain 

 symmetrical. The duplication can extend to the terminal 

 leaflet and turn a vein of this, either on one side or on 

 both sides, into the primary vein of a new leaflet. In this 

 way the 6- and 7-merous leaves arise : the former are 

 asymmetrical, the latter symmetrical. 



The statistical examination of large numbers proves 

 that the symmetrical leaves predominate over the asvm- 

 metrical ones. The plant seems to prefer to retain its 



^Delptno, Tcon'a generalc dcUa FilJnfassi, 1883, p. 197. 



