172 Heredity and Eugenics 



The saltationist school, aside from a considerable num- 

 ber of clearly formulated questions, has very clearly raised 

 the issue as to whether changes in the constitution of the 

 germinal material are accomplished by the slow quantita- 

 tive accumulation of useful variations, or take place by 

 sudden steps, appearing with discontinuity in the end result. 

 Much experience with this method of quantitative accumula- 

 tion had given adequate reason to distrust it as a particularly 

 potent means of inducing experimental change, and refuge 

 not infrequently had been sought in the soul-satisfying 

 myths of germinal selection, orthogenesis, isolation, growth 

 force, bathmic force, and many other intricately contrived 

 and all inclusive hypotheses, but all were found utterly 

 useless for actual experimental investigation and analysis, 

 such as is demanded in physical and chemical science. 



In seeking for an outlet from the culs-de-sac of evolu- 

 tionary science as it existed in the last quarter of the nine- 

 teenth century, DeVries concluded that change, per saltum, 

 was quite as liable to be a real method of transmutation and 

 sought to put it to a test by seeking in nature for species 

 of plants that were undergoing this kind of change if such 

 existed. Darwin had already noted the frequent occurrence 

 of large sudden departures in both plants and animals, but 

 was of the opinion that both large, sudden, and small 

 fluctuations were operative in transmutation phenomena. 



The discovery of 0. Lamar ckiana (Fig. 62) in an 

 abandoned field near Hilversum in Holland, into which 

 it had escaped from a near-by park, provided most favor- 

 able material for DeVries' further study. Here it grew in 

 quantity with two apparently newly arisen derivative forms, 

 0. laevifolia and O. brevistylis. Plants from this waste 

 land were taken into the botanic gardens of Amsterdam 



