896 



SCIENCE 



[N. S. Vol. XXXI. No. 



theories are correct or not, wliolly or 

 partly, is of far less importance to agri- 

 culture than the stimulus he has given to 

 the experimental study of plant variation. 

 Not only has he done a vast amount of 

 this sort of work himself, but he points 

 out very clearly numerous problems 

 awaiting the investigator. 



It is remarkable that thus far so little 

 has been done in attempting to produce 

 anew the varieties of cultivated plants by 

 beginning with the wild plant and con- 

 ducting the work under critical scientific 

 conditions. This is perhaps impossible 

 in the case of our most important plants 

 which have been cultivated since prehis- 

 toric times— and of whose original form 

 we are in many cases ignorant, but it 

 surely is a feasible and logical method of 

 procedure in the case of plants domesti- 

 cated in recent times, as is the ease with 

 many ornamentals. There is, I believe, 

 no dissent from the statement that culti- 

 vated plants show far greater diversity 

 than their wild progenitors. Is this 

 greater diversity merely due to intensifi- 

 cation of differences already possible of 

 discernment in the wild plant, or do really 

 new types appear under the stimuli of 

 cultivation? To use a simple example, 

 ImTpatiens sidtani, an African ornamental, 

 was first introduced into cultivation about 

 twenty years ago, only a single color be- 

 ing then known. It now occurs in four 

 distinct colors. Have these arisen under 

 cultivation or were they found as wild 

 sports 1 A more complex case. Phlox 

 drummondii is a native to Texas and not 

 very variable, so far as known only pink, 

 purple and red varieties existing wild. 

 It was introduced into cultivation about 

 seventy-five years ago. There is now a 

 bewildering array of color varieties— both 

 with entire and with fringed petals. In 

 the so-called star of Quedlinburg varieties 



the central tooth of the fringed varieties 

 is prolonged into a lobe as long or longer 

 than the petal. In the wild form there is 

 apparently no hint of such a character. 

 It ought to be no difficult task to repeat 

 the evolution of these forms under test 

 conditions and thus get a full record of 

 what takes place. Until this is done our 

 picture of the process must remain incom- 

 plete. How far extreme conditions as to 

 soil, heat, moisture and other external 

 factors may affect the process of varia- 

 tion, especially permanent variations, is 

 one of great interest and importance. Our 

 wide range of soils and climates gives us 

 unusual opportunity to plan such investi- 

 gations. To start anew with the wild 

 forms of our most important crops, wheat, 

 oats, corn, beans, potato, etc., is rendered 

 difficult owing to our ignorance of the 

 wild progenitors of these crops. Why 

 these should have disappeared if such is 

 the case is very puzzling. Aaronsohn has 

 recently discovered in the mountains of 

 Palestine what are probably the wild 

 originals of wheat, of barley and of rye. 

 As this country was long ago well ex- 

 plored botanically, the question at once 

 arises — why were not these plants found? 

 Aaronsohn offers a humorously simple 

 explanation, namely, that no botanist ever 

 collects a cultivated plant and no agron- 

 omist ever looks at a wild one. Perhaps 

 a similar explanation may account for our 

 ignorance of corn and other American 

 natives in the wild state. A particular 

 interest in knowing the wild form of such 

 plants is to be able to measure the progi-ess 

 that has been made by cultivation. 

 Another is to determine how quickly it 

 may be possible to breed up to the approx- 

 imate standards of the long-cultivated 

 strains. There is a general belief that 

 great improvements can be made in the 

 early processes of breeding for improve- 



