44 MISCELLANEOUS PAPERS. 
hybrids. Should the increased yield of hybrid plants prove to be 
greatest in the first generation or should the complete elimination of 
self-fertilization prove an important factor, it 1s quite practicable to 
maintain a continuous supply of hybrid or cross-pollinated seed. 
A study of the habits of the plant from the standpoint of cross- 
fertilization makes apparent the nature of the so-called “ barren 
stalks,” which may be thought of as an adaptation to avoid self- 
pollination. The elimination of these proterandrous plants results 
in increasing the percentage of self-pollinated plants and is a prac- 
tice of doubtful value. 
The ill effects of inbreeding and selection for increased yield and 
vigor have tended to neutralize each other, and the consequent lack 
of continued improvement has lent color to the idea that continuous 
selection is imeffective. With characters that are not affected by 
decreased vigor continuous advance has been made by selection. 
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