MODERN BIOLOGY 587 



to create a better human race and desired that all research work should serve 

 that object; he gave to the science that he placed highest of all the name 

 of "eugenics," a name that has become universally accepted. 



A new phase in the history of heredity research was introduced by Hugo 

 DE Vries. Born at Haarlem in 1848, he studied at Wiirzburg under Sachs, 

 held various posts in Germany, and finally became professor at Amsterdam. 

 He applied himself first to the study of plant physiology and published val- 

 uable results of his investigations into the pressure conditions in plant-cells. 

 At the same time he speculated over Darwinistic problems. He, too, pro- 

 duced a theory of life-entities, which he called "pangens," by which he 

 meant those qualities in the organism which are capable of independent 

 variation, and each of which must, in his view, be represented by one ma- 

 terial entity. Like so many other biologists of the younger generation, how- 

 ever, he entertained doubts as to the ability of the traditional Darwinism 

 to solve the problem of evolution. He was especially preoccupied with the 

 undeniable fact that the species in nature remain constant and that the slight 

 transitions whereby, according to the old theory, one species is converted 

 into another can never be observed; the species is a self-contained entity, 

 and yet the conversion of species must have taken place in the course of 

 the ages. Kolliker's previously mentioned theory of sudden changes of species 

 seemed to him to offer the possibility of adjusting this inconsistency, nor, 

 indeed, had Darwin himself denied the existence of sudden "single varia- 

 tions." It was only a question of obtaining actual proof of the existence 

 of such changes. Eventually de Vries believed that he had found it in CEno- 

 thera lamarckiana (evening primrose), a plant introduced from America, which 

 has spread over various European countries. This plant grew in masses in 

 a meadow in the neighbourhood of Amsterdam and exhibited, besides a 

 number of typical forms, some few with an entirely divergent appearance. 

 A number of specimens having been transferred to a garden and there al- 

 low^ed to multiply by self-fertilization, it was discovered that in the course 

 of a few years there developed out of seed of the old species not only forms 

 similar to it, but also isolated specimens With, well-marked new species- 

 characters, which were retained for the purpose of further cultivation: 

 among them a dwarf form, a markedly latifoliate form, and some others. 

 Here, then, we get, according to de Vries, a species that suddenly "ex- 

 ploded," as he expresses it, and gave rise to a number of new species, each 

 with definite characteristic features. This case shows, according to him, how 

 the species in general have arisen; the species, he says, are no arbitrary 

 groups, but completely independent entities, delimited in time and space, 

 which originate through old species' suddenly disintegrating into a number 

 of new forms; of these some are capable of life and survive unchanged until 

 the next mutation, while others cannot sustain the struggle for existence 



