DEVELOPMEISTT OF TUBERS IN THE POTATO. 



vals of approximately one month each, beginning one month after 

 germination, showed that tuber development continued during the 

 entire period, though the rate of increase was diminished during the 

 fourth month. Analyses of the tubers harvested at the end of each 

 monthly period showed that with respect to the mineral constituents 

 there was little change in composition after the first month. Those 

 produced during the first period, however, contained slightly higherper- 

 centages of these constituents than were found in the later harvests. 



Chemical studies by Jones and White (4) with the Delaware and 

 White vStar varieties, dug at intervals of 10 days from August 4 to 

 November 3, 1898, 

 and from August 12 

 to October 11, 1899, 

 showed that the most 

 important changes 

 occurring during the 

 period of the experi- 

 ment were those of 

 yield rather than 

 composition. There 

 was, however, a very 

 small decrease in the 

 percentage of dry 

 matter and nitrogen- 

 free extract and a 

 slight trend toward 

 an increase in the 

 protein, ash, and 

 crude fiber as the 

 crop approached ma- 

 turity. 



Studies of the com- 

 position of tubers be- 

 fore and after growth 

 had ceased led Prunet 

 (8) to conclude that 

 during the period of 

 growth the nutritive 

 substances are uni- 

 formly distributed throughout the tuber, but after full size has been 

 reached there is a movement of these substances toward the vicinity 

 of the apical buds. 



Data regarding the growth of tubers after frost were obtained by 

 Follstad (1), who weighed one tuber from each of four hills on Sep- 

 tember 13, 16, 20, and 27, weighing the same tubers on each of the 

 different dates without detaching them from the stolons. The 

 leaves had previously been killed by frost on September 10. The 



Fio. 2,— Plant of the Charles Downing variety of potato, showing 

 the relatively long stolons on which the tubers are born e. 



