102 LOCK : STUDIES T\ PLANT RREEDTNO 



<>n a large plot of fall plants, especially when, as sometimes 

 happen 1 ninal flowers are produced on a seed-bearing 



Rpike. 



In the following experiments there was now and then evi- 

 dence of stray pollen grains having eseaperl owing to the latter 

 cause, but never in sufficient numbers to vitiate a statistical 

 result. 



DESCRIPTION OF STRAINS USED IN THE 

 EXPERIMENTS. 



I. (W. D.) "Boone County' white dent corn. Loose 

 grains of this variety were obtained from Mr. Webber of the U. 

 S. Dept. of Agriculture, Washington. A figure of a perfect 

 cob of this strain appears in Webber and Bessy's pamphlet (74), 

 1889, in which there is also given a picture of the type from 

 which it was derived by selection. The Cobs of the first 

 generation grown at Peradeniya — sown December. 1902, in 

 comparatively poor soil — resembled the latter type, but were 

 smaller and less perfect. None were covered to the top with 

 grains as in the improved "Boone County " type. By dint 

 of ■ iictul selection and heavy manuring of the plants at my 

 disposal I was able in four generations to obtain a large per- 

 centage of perfect cobs of the improved type. The shape of 

 the grains meanwhile remained perfectly constant, being flat, 

 elongated and much indented at the apex, and they were 

 Always ;>urc white. 



This result is interesting in more than one way. [n the first 

 place it very clearly illustrates the fact thai races produced by 

 selection owe their continued existence to the continuance of 

 the process under the proper conditions. And in the second ii 

 entirely discredits the idea quoted by Darwin from Metzger, 

 that corn I rred to new conditions reverts to the type 



llent ;u the new country. 



What is clearly the true explanation of Metzger's phenomena, 

 namely the effect of cro sing vrith the local form, has been clear- 

 ly pointed nut by de Vries, and Vernon's recent use of these 



