1918] GERICKE—SOLANUM 351 
Series IX and X represent the third and second generations of a 
continuous no-rest treatment series. The seed potatoes for these 
series were halved; one part was planted and the other half kept 
for analysis. The purpose was to compare the analysis of tubers 
which had produced a crop with that of normal potatoes and thus 
learn how much of the plant food in the tubers is used in the growth 
ofacrop. The results obtained in series LX and X were similar to 
those already stated for other no-rest period series. One-stalked 
plants were produced in all cases. A period of 46 days was required 
for series IX to appear above ground, while the plants of series X 
appeared on an average of 39 days. The average length of the 
actual growing period above ground was 104 days, which is about: 
4 weeks longer than that of series I, VII, and VIII, the normal ones 
for this variety of potato. 
The seed tubers of series IV and V were recovered and planted 
as already mentioned. The appearance of the plants above ground 
from this second planting occurred in 9 and 11 days, which was 
much less time than that required for their appearance at the first 
planting. The actual growing period of the plants above surface 
was 97 and ror days, a long period, similar in this respect to the 
case of their first planting. Three to four stalks developed from 
the tubers instead of one stalk, as was the case in the first crop of 
this series. 
That the growth of some plants can be affected by rest period 
changes in the composition of its seeds or bulbs has been shown 
by this experiment with the potato. The most significant effect 
observed was the variation in the length of the growing period, 
both as to the length of time required for the plants to appear and 
the length of the actual growing period above ground. The pota- 
toes planted immediately after harvest to the depth of 3 inches 
produced one-stalked plants. All of these forms of plant responses 
undoubtedly were influenced by certain chemical changes in the 
tuber indicated to some extent by the various investigations men- 
tioned. That the after-ripening changes in the potatoes used in 
this experiment, because of the conditions imposed upon the seed 
tubers, may have been affected in the rate, quantity, and specificity’ 
of their reactions, seems a reasonable conclusion. 
