DEVELOPMENT 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 higher per- 
centages of these constituents than were found in the later harvests. 
Chemical studies by Jones and White (4) with the Delaware and 
White Star 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 
Fig. 2.— Plant of the Charles Downing variety of potato, showing 
the relatively long stolons on which the tubers are borne. 
