1918] GERICKE—SOLANUM 349 
_ after-ripening processes of the potatoes, therefore, proceeded in 
the soil, but the degree and perhaps the specificity of the processes 
were different from those occurring in the tubers under ordinary 
conditions of storage. That the 56 days of rest period did not 
materially shorten the total time required for the seed potatoes 
harvested from series I to produce a crop is evident from the fact 
that the total time required for series II and III to produce a crop 
from the harvest of the tubers from which they grew, namely, 
series I, is about the same as indicated in the sum of the rest period 
and growth period of the two series. The germination of one bud 
in the tubers of the no-rest period may indicate the localization 
of the products of the after-ripening processes. The failure of 
other buds to sprout while the one stalk was growing and maturing 
a crop could have been due in part to the insufficiency of proper 
plant food in the tuber. Furthermore, the production of sub- 
stances by the growing plant which could act inhibitively to the 
germination of other buds of the tubers may offer a partial explana- 
tion for the failure of other stalks to make their appearance. The 
fact that the seed tubers of the no-rest series remained in the 
ground for a long time without decay may indicate the presence of 
some protective agent, or that the condition of the tuber was such as 
to preclude bacterial decomposition. The probable lack of both 
_ Sugar formation and the hydrolysis of other food material in the 
no-rest period tubers may be causes that have not permitted the 
development of the organisms of decomposition. 
In series IV, another no-rest period set, half tubers of 82 and 
89 gm. weight respectively were used for planting. The time 
required for the plants to appear above ground was 77 and 74 
days for the duplicate pots. The actual growing period of the 
visible plants averaged 100 days, and the time from planting to 
harvest averaged 175 days. Similarly to series H, just one- 
stalked plants were produced, indicating the germination and 
growth of one bud for each half tuber. 
Series V, another no-rest period set, was planted with whole 
tubers of 53.6 and 56.9 gm. weight from the crop of series ILI. 
The results obtained for this series were similar in all respects to 
those obtained for series IV, as the results in table HII show. The 
