Plant-Breeding for Farmers. 171 



By examining the table it will be seen that hill No. 7 which had the 

 highest yield of the original ten hills selected, in each of the three years 

 during which the selections continued, gave a very high yield, and the 

 highest average yield of any for the three years. This strain would seem 

 to possess unquestionable merit and to be one to propagate from. 



In advocating the selection of but fifty tuber-units and the planting 

 of ten tubers only from each select unit the writer has had in mind 

 the reduction of the work to a comparatively simple plan which would 

 be possible of execution by many growers. It would unquestionably be 

 better to handle larger numbers if the grower is so situated that he can 

 take the time for it. It is, however, better to use comparatively small 

 numbers carefully than to attempt to handle large numbers and find the 

 work too extensive. The plan provides, however, for testing the yield 

 of 500 tubers each year and this number should give opportunity to 

 secure good selections. The method of selection here proposed, which 

 Professor J. B. Norton has aided the writer in devising, is based on the 

 tuber and its yielding capacity as a unit. It is somewhat difi^erent from 

 any method which has been used heretofore, and is somewhat complex. 

 It is primarily the same as the ordinary hill selection, but is believed 

 to furnish a more accurate method of judging the yielding capacity of 

 the mother tuber which is fundamentally what the hill selection is supposed 

 to do. The difficulty in cutting uniform sized pieces with eyes equally 

 favored renders the ordinary hill method very unreliable for general use, 

 and the tuber-unit plan is believed to avoid this difficulty. 



SOME IMPORTANT BOOKS AND BULLETINS ON SUBJECTS DIS- 

 CUSSED IN THIS BULLETIN. 



On the principles am! methods of breeding. 



Bailey. L. H. Plant-breeding. 4th edition. New York, Macmillan & Co. 1906. 

 De Vries, Hugo. Plant-breeding. Chicago. Open Court Publishing Co. 1907. 

 Davenport, E. Principles of Breeding. Boston, Ginn & Co. 1907. 

 East, E. M. The Relation of Certain Biological Principles to Plant-breeding. 



Bull. 158, Connecticut Agric. Exp. Station. New Haven. Conn. 

 Hays, W. 1\I. Plant-breeding. U. S. Department of Agric, Div. Veg. Phys. and 



Path. Bull. 29. 1901. 

 Hunt. T. F. The Cereals in America. New York. Orange Judd Co. 1906. 

 Webber, H. J. Improvement of Plants by Selection. Yearbook U. S. Dept. of 



Agric. i8g8 pp. .355-376. 

 American Breeders' Association, Reports Volumes I, II, and III, Washington, 



D. C. (Copies of these reports can be secured at $i.co per volume from Hon. 



W. M. Hays, Secretary, Washington, D. C). 



On corn-breeding. 

 Hartley, C. P. Improvement of Corn by Seed Selection. U. S. Dept. Agric. 



Yearbook 1902 pp. 539^552. 

 Hartley, C. P. Production of Good Seed Corn. U. S. Dept. Agric. Farmers, 



Bull. 229 (1905). 



