POTATO BEEEDING AND SELECTION. 23 



produce the best plant) for now^ fourteen years. My main object here has been absolute 

 freedom from disease, and these potatoes are now descended from a line of single tubers, 

 each the best plant of the year and absolutely healthy; and concurrently with the 

 endeavor to wipe out all hereditary tendency to disease, I have always kept in full 

 \T.ew the point of increasing productiveness. The result may be thus shortly stated : 

 Dividing the first twelve years into three periods, the average number of tubers upon 

 the annual best plant selected was, for the first period of four years, 16; for the second 

 period of four years, 19; for the last period of four years, 27; or nearly double the 

 number produced during the first series of four years. And if, as I might very 

 fairly have done, I had confined the fh-st period to the first three years (instead of four), 

 the last period would have shown an average of 27 tubers against 13 in the first period, 

 or more than double. 



The care mtb. which this experiment was apparently conducted 

 and the selection of the strongest, most disease-free, and productive 

 plants would seem to mdicate that Hallet, at least, had a very clear 

 conception of the advantages of selection in building up vigorous 

 and productive strains of potatoes. 



Carriere says:* 



The potato furnished us with examples of modifications just as remarkable as those 

 which we have reported for beans and for corn. . . . Every year, in reality^ when 

 we harvest the tubers and wish to conserve the purity of the variety, we are obliged 

 to purify, that is to make a choice and reject those which, as we say, have degener- 

 ated. . . . The modifications in the potato may occur equally well in the underground 

 parts; that is what has happened in the variety called Pousse-debout. The name 

 Pousse-debout has been given to this variety because the tubers which it produces, 

 instead of being placed flat, or nearly so, in the soil, are arranged one against the. 

 other, much like pieces of wood are disposed for transformation into charcoal. 



It is further stated that the Marjolin potato is a variety possessing 

 the peculiar quality of never flowering and of being very early, but 

 notwithstanding this fact it is continually producing plants which 

 flower and produce seed, and which, owing to this fact, are not as 

 early as the parent plant. In yet another variety, the Chardon, 

 Carriere observ^ed transformations in color of flowers, shape of tubers, 

 and season of ripening, and this, too, in a strain which had been under 

 observation for -a long time without having previously shown any 

 variation whatsoever. 



Golf's ^ experiments in 1884 and 1885 demonstrated that tubers 

 frf>m productive plants gave larger yields than tubers from unpro- 

 ductive plants, the total gain being a little more than 24 per cent. 



In 1897 Fischer '' began some selection work with the potato, in 

 which variations in productiveness, shape, and starch content of 



• Carrlfere, E. A, Production et Fixation des Varl<H<5s dans les Vc'gdtaux, 72 p., IHus. Paris, 1805. (See 

 p. 40-J1.) 



* Qott, E. 8. Experiments witii tuijers tal<cn from productive and unproductive liills. N. Y. ((ioneva) 

 Agr. Exp. Sta.,3d Ann. Upt., 1HH4, p. :V)]-:m, Alimny, IKM; 4tli Ann. lipt., IKR.'i, p. 232 23r), Allmiiy, IssG. 

 (A copy of this 4th Uopt. wa.s published also at Jloche.sl<T. Jn Liil3c<jpy tlic reference will be foiiiid on f). 

 204-207.) 



» PLvhcr, Max. KarlcjiTnlzuehtunKK- urid Ani)uuv(Tsucfic. hi I''(llilliij;'s Laiidw. /l^;., .Inlirj.;. I'.i, IV()(). 

 Heft H, p. -.m V)7; Hcfl {), J). 34.1 :r)2; llefl 10, p. :UiO-372. 



