358 READINGS IN EVOLUTION, GENETICS, AND EUGENICS 
mentioned, namely, albida, nannella, lata, oblonga, 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 Hilversum field, or else raised from seeds that had been collected 
there. These facts show that the new species are not due to cultiva- 
tion, 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. 
From the point of view of the mutation theory, species are no 
longer looked upon as having been slowly built up through the selec- 
tion of individual variations, but the elementary species, at least, 
appear at a single advance, and fully formed. This need not neces- 
sarily mean that great changes have suddenly taken place, and in 
this respect the mutation theory is in accord with Darwin’s view that: 
extreme forms that rarely appear, “sports,” have not furnished the 
material for the process of evolution. 
As De Vries has pointed out, each mutation may be different from 
the parent form in only a slight degree for each point, although all 
the points may be different. The most unique feature of these muta- 
tions is the constancy with which the new form is inherited. It is 
this fact, not previously fully appreciated, that De Vries’s work has 
brought prominently into the foreground. There is another point of 
great interest in this connection. Many of the groups that Darwin 
recognized as varieties correspond to the elementary species of De 
Vries. These varieties, Darwin thought, are the first stages in the 
formations of species, and, in fact, cannot be separated from species 
in most cases. The main difference between the selection theory and 
the mutation theory is that the one supposes these varieties to arise 
through selection of individual variations, the other supposes that 
they have arisen spontaneously and at once from the original form. 
The development of these varieties into new species is again sup- 
posed, on the Darwinian theory, to be the result of further selection, 
