Trifolium Prafcusc Quinque folium. 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, 1 occurs in my race also, and if it 
affects 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 quinquefoliate leaf 
which is usually in the majority ; the remaining types are 
grouped round it in accordance with OUETELET'S law, so 
far as the tendency to symmetry permits this. For it is 
clear that this tendency does not favor the regularity 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, 
but 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 asym- 
metrical ones. The plant seems to prefer to retain its 
1 DELPTNO, Teoria general? dclla FiJlotassi, 1883, p. 197. 
