35 
the shoot of wanella is 31.84 + 3.16 per cent. while that of 
Lamarckiana is only 5.37.44 per cent. The coefficient of 
variability for the number of branches of rudrinervis is 15.0 + 1.7 
per cent. and for the total length of the branches is 48.7 + 5.1 
per cent. and for the ratio between width and length of the leaves 
is 10.30 + .20 per cent., for the number of branches of Lamarck- 
jana 15.7+1.7 per cent., for the total length of the branches 
Fie, 13. One of the types (No. 2.27) of the hybrid between Lamarck’s evening- 
primrose and the common evening- primrose. 
20.2 + 2.2 per cent., and for the ratio between the width and 
length of the leaves 9.53 + .22 per cent. 
The wide variability of the mutants does not, however, seem to 
result in any diminution of the gap that separates them from the 
parent-form, and no movement in this direction has been observed 
in the long period which has elapsed since the new species came 
