296 Evolution and Adaptation 
shows the mutations that arose between 1887 and 1899 
from these plants. The seeds were selected in each case 
from self-fertilized plants of the /amarckiana form, so that the 
new plants appearing in each horizontal line are the descend- 
ants in each generation of /amarckiana parents. It will be 
observed that the species, O. oblongata, appeared again and 
again in considerable numbers, and the same is true for 
several of the other forms also. Only the two species, O. 
gigas and O. scintillans, appeared very rarely. 
Thus De Vries had, in his seven generations, about fifty 
thousand plants, and about eight hundred of these were muta- 
tions. When the flowers of the new forms were artificially 
fertilized with pollen from the flowers on the same plant, or 
of the same kind of plant, they gave rise to forms like them- 
selves, thus showing that they are true elementary species.’ 
It is also a point of some interest to observe that all these forms 
differed from each other in a large number of particulars. 
Only one form, O. scéztillans, that appeared eight times, is 
not constant as are the other species. When self-fertilized 
its seeds produce always three other forms, O. sczntillans, 
O. oblongata, and O. lamarckiana. It differs in this respect 
from all the other elementary species, which mutate not more 
than once in ten thousand individuals. 
From the seeds of one of the new forms, O. levzfolia, 
collected in the field, plants were reared, some of which were 
O. lamarckiana and others O. levifolia. They were allowed 
to grow together, and their descendants gave rise to the same 
forms found in the /amarckiana family, described above, 
namely, O. lata, elliptica, nannella, rubrinervis, and also two 
new species, O. spatulata and leptocarpa. . 
In the Zaza family, only female flowers are produced, and, 
therefore, in order to obtain seeds they were fertilized with 
1 0. lata is always female, and cannot, therefore, be self-fertilized. When 
crossed with O. /amarckiana there is produced fifteen to twenty per cent of 
pure éafa individuals. 
