400 



SCIENCE. 



[N. S. Vol. XX. No. 508. 



but, on the other hana, their occurrence can 

 be predicted in some cases with enough 

 probability to justify the trial. Color 

 changes in flowers, double flowers, regular 

 forms from labiate types, and others have 

 been produced more or less at will in my 

 garden, and under conditions which al- 

 lowed of a close scientific study. The sud- 

 denness of the changes and the perfection 

 of the display of the new characters from 

 the very beginning were the most striking 

 results. 



These facts, however, only gave an ex- 

 perimental proof of phenomena which were 

 historically known to occur in horticulture. 

 They threw light upon the way in which 

 cultivated plants usually produce new 

 forms, but between them and the real 

 origin of species in nature the old gap 

 evidently remained. 



This gap, however, had to be filled out. 

 Darwin's theory had concluded with an 

 analogy, and this analogy had to be re- 

 placed by direct observation. 



Success has attended my efforts even 

 on this point. It has brought into my 

 hands a species which has been taken in 

 the very act of producing new forms. This 

 species 'has now been observed in its wild 

 locality during eighteen years, and it has 

 steadily continued to repeat the phenom- 

 enon. I have brought it into my garden, 

 and here, under my very eyes, the produc- 

 tion of new species has been going on, 

 rather increasing in rate than diminishing. 

 At once it rendered superfluous all consid- 

 erations and all more or less fantastical 

 explanations, replacing them by simple 

 fact. It opened the way for further in- 

 vestigations, giving nearly certainty of a 

 future discovery of analogous processes. 

 Wlaether it is the type of the production 

 of species in nature or only one of a more 

 or less large group of types can not yet be 

 decided, but this is of no importance in 

 the present state of the sub.ject. The fact 



is that it has become possible to see species 

 originate, and that this origin is sudden 

 and obeys distinct laws. 



The species which yielded these impor- 

 tant results is an American plant. It is 

 a native of the United States, and nearly 

 allied to some of the most common and 

 most beautiful among the wild flowering 

 plants of this country. It is an evening 

 primrose, and by a strange but fortunate 

 coincidence bears the name of the great 

 French founder of the theory of evolution. 

 It is called 'Lamarck's evening primrose/ 

 and produces crowns of large and bright 

 yellow flowers, which have even secured it 

 a place amongst our beloved garden plants. 



The most interesting result which the ob- 

 servation and culture of this plant have 

 brought to light is a fact which is in direct 

 opposition to the current belief. Ordi- 

 narily it is assumed that new species arise 

 by a series of changes in which all the 

 individuals of a locality are equally con- 

 cerned. The whole group is supposed to 

 be modified in a distinct direction by the 

 agency of the environmental forces. All 

 individuals from time to time intercross, 

 and are thereby assumed to keep equal pace 

 in the line of modification, no single one 

 being allowed to go distinctly ahead of 

 the others. The whole family gradually 

 changes, and the consequence would be that 

 the old form disappears in the same degree 

 as the new makes its appearance. 



This easy and plausible conception, how- 

 ever, is plainly contradicted by the new 

 facts. There is neither a gradual modifica- 

 tion nor a common change of all the indi- 

 viduals. On the contrary, the main group 

 remains wholly unaffected by the produc- 

 tion of new species. After eighteen years 

 it is absolutely the same as at the beginning, 

 and even the same as is found elsewhere in 

 localities where no mutability has been ob- 

 served. It neither disappears nor dies out, 



