Thus De Vries had, in his seven generations, about fifty thousand plants, and about eight hundred of these were mutations. 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 themselves, thus showing that they are true elementary species.[26] It is also a point of some interest to observe that all these forms differed from each other in a large number of particulars. Footnote 26: _O. lata_ is always female, and cannot, therefore, be self-fertilized. When crossed with _O. lamarckiana_ there is produced fifteen to twenty per cent of pure _lata_ individuals. Only one form, _O. scintillans_, that appeared eight times, is not constant as are the other species. When self-fertilized its seeds produce always three other forms, _O. scintillans_, _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. lævifolia_, collected in the field, plants were reared, some of which were _O. lamarckiana_ and others _O. lævifolia_. They were allowed to grow together, and their descendants gave rise to the same forms found in the _lamarckiana_ family, described above, namely, _O. lata_, _elliptica_, _nannella_, _rubrinervis_, and also two new species, _O. spatulata_ and _leptocarpa_. In the _lata_ family, only female flowers are produced, and, therefore, in order to obtain seeds they were fertilized with pollen from other species. Here also appeared some of the new species, already mentioned, namely, _albida_, _nannella_, _lata_, _oblongata_, _rubrinervis_, and also two new species, _elliptica_ and _subovata_. De Vries also watched the field from which the original forms were obtained, and found there many of the new species that appeared under cultivation. These were found, however, only as weak young plants that rarely flowered. Five of the new forms were seen either in the Hilversam field, or else raised from seeds that had been collected there. These facts show that the new species are not due to cultivation, and that they arise year after year from the seeds of the parent form, _O. lamarckiana_. Conclusions From the evidence given in the preceding pages it appears that the line between fluctuating variations and mutations may be sharply drawn. If we assume that mutations have furnished the material for the process of evolution, the whole problem appears in a different light from that in which it was placed by Darwin when he assumed that the fluctuating variations are the kind which give the material for evolution.