546 KELLICOTT : PERIODICITY IN ROOT OF ALLIUM 
the preceding one, but still no correlation is observable between 
variations in temperature and rate of elongation. 
Another record, curve //, FIGURES 6 and 7, was made at the 
same time as curve J and under identical conditions. The points 
of dissimilarity between the two are of degree rather than of kind. 
There is just the same pronounced minimum at 11 p. m. The 
primary maximum however occurs somewhat earlier, that is at I 
p.m. The secondary maximum occurs at the usual hour. The 
secondary minimum about noon is not very clearly marked but is 
indicated at 11 a.m. On the whole the secondary waves are all 
less definite than in the curves previously described. 
Finally, another record made under conditions identical with 
those of curve //I, FIGURE 7, must be considered. This record 
is illustrated as curve //J, FIGURE 6. This is the only root ob- 
served during the ascent of the grand period of growth and most 
of its very evident peculiarities may be explained in connection 
with this fact. The rate of elongation reaches its primary maxi- 
mum at 9 p.m. Another maximum is marked definitely at 3 P- 
m. and the rate was increasing again steadily when the observa- 
tion ended at g a. m., as if to mark another maximum. A very 
extensive minimum occurs between 1 and 5 a. m., and at the 
beginning of the observation a minimal period extends from 9 4. 
m. to 1 p.m, The features of the curve are all remarkably regu- 
lar and well marked. The total amount of elongation during 
the 24 hours was only 13.5 mm. There is no correlation between 
the rate of elongation and the comparatively slight variations in 
temperature. 
The principal peculiarities of this record are due to the ap- 
pearance of the primary maximum and minimum about five hours 
later than normally and to the absence of the secondary waves in 
the early morning. A possible explanation of these peculiarities 
may be the following. From the comparative levels of the begin- 
ning and end of the curve and from the small amount of elonga 
tion of the root, we are evidently concerned here with a root 
which has not yet reached the maximum of its grand period of 
growth. Such a young root is growing with a greater vigor, has — 
a greater momentum so to speak, and as a consequence is not 
affected by stimuli (external or internal) which would affect roots 
