338 PLANT-BREEDING 



century ago, and have spread widely over various countries. 

 Both have become quite common with us, but prefer dif- 

 ferent Hfe-conditions. Now it is very interesting to note 

 that one of them, the smah- flowered form or Oenothera 

 muricata, prefers the proximity of the sea-shore, whilst 

 the common species or (E. biennis prefers inland fields and 

 places. On the sand-dunes along the coast of Holland, this 

 difference in stations is very striking, the small flowering 

 type being almost limited to a region of a few miles along the 

 coast. 



How can this noticeable difference be explained ? Espe- 

 cially, how did the muricata acquire its love for the sea-air 

 and the sea- winds? All our knowledge of the dispersion 

 of the evening primroses points to some part of the middle 

 states of the United States of America as their original 

 habitat, and so it seems evident that even the muricata was 

 originally an inland plant, springing up far from any influence 

 of the sea. 



From this special instance we may conclude that at least 

 in many cases, the geographical distribution of wide-spread 

 plants is governed by qualities acquired quite independently 

 of their present life-conditions. Innate propensities govern 

 their dispersion, and have determined where they should be 

 crowded out and where they could multiply themselves. 

 In order to make this conclusion still more convincing, I 

 might draw your attention to the chronological side of the 

 question. We are trying to explain the constitution of 

 forms on the ground of the conditions under which they 

 are now living. But in doing so, we forget how very old 

 they are, and how much nature may have changed since 

 their first origin. Many of our most common species are 

 known to be older than the glacial periods, their fossil 

 remains being found in the upper tertiary deposits (e. g. 

 Statiotes aloides). If they have endured these dreadful 



