466 The American Naturalist. [May, 
1. The apparatus as set up indicated growth by cylinder- 
tracings. 
2. A possible indication of periodicity in the growth may 
have manifested itself. 
Further than this one could not go under the conditions of the 
experiment. 
Desiring to obtain more perfect results, and to solve the 
question as to the manner of growth of the tuber, the improved 
method of setting up the apparatus was developed as described 
above, and the first experiment gave some interesting results. 
The method of culture in water employed by De Vries® in the 
study of roots was contemplated, but rejected on account of 
certain practical difficulties. 
The experiment began with a tuber about 34-inch in diameter. 
~ At this time the full-sized top of the plant had begun to perish 
from the effects of mildew. After attachment the registering 
needle gave two or three sharp drops, owing to the stretching of 
strings and general getting into equilibrium of the apparatus. 
After this stage was passed the needle began dropping very 
gradually. This slow descent was continued from eight o'clock 
in the evening until about eight o’clock in the morning. At this 
time the drop ceased, and horizontal tracings continued until about 
1.30 P.M., when a short, abrupt hour’s drop was registered, fol- 
lowed by a longer one, then by one shorter than the second but 
longer than the first, next by one longer than any, closely 
succeeded by another long one. After this the registrations were 
short, and the regular, gradual fall until 8 a.m. began. Here 
again the horizontal mark began and continued until 2 P. M., when 
a second drop began, on a somewhat smaller scale than the ie 
registered the first day. The total extent of the second day's 
maximum, between 2 P. m. and 8 P. m., was about one-half of the 
first day’s maximum. The third day the same tracings COM- 
tinued at the same hours,—only the tracings of the maximum 
were very much reduced, so as to be not more than onesie 
the total length of the second day’s tracings. The fourth day’ | 
tracings were like those of the second day in almost ev: ery par 
3 Landwirthschaftliches Jahrbuch, 1880, Bd. IX., p. 37. 
