MUTATION IN (ENOTHERA 143 
generations. The net result of his experiments was 
this : out of about 50,000 individuals which were grown 
to a recognisable stage, more than 800 showed muta- 
tion—that is to say, they differed specifically from 
the parent O. Lamarckiana. The 800 individuals 
belonged to about fifteen new kinds, most of which 
appeared repeatedly, though some were more frequent 
than others. The process of mutation had, therefore, 
taken place in about 14 per cent. of the seedlings which 
were grown, and owing to various reasons this estimate 
is probably considerably too low. For example, many 
of the new forms were very weakly, and often died 
before it was possible to distinguish them. Others, 
again, could not be recognised until an advanced stage 
of their growth had been reached, whereas only a small 
proportion of the seedlings raised could be grown after 
they had reached any considerable size, owing to con- 
siderations of space. 
We cannot now follow de Vries very far into his 
elaborate account of his new species and of the way 
in which they originated ; a few general remarks only 
must suffice. Many of the new forms were recognis- 
able as quite young seedlings, notably O. albida, 
others not until a much later period of their growth. 
O. gigas was the finest and strongest of the new forms, 
but only made its appearance on two occasions. 
O. lata also appeared to be as strong as the parental 
type, whilst two other forms were able to survive in 
nature in competition with the original species, as 
has been already described. Other forms which were 
grown and flowered were plainly less well fitted for 
