536 KELLICOTT: PERIODICITY IN ROOT OF ALLIUM 
The primary maximum occurs at 8 p. m., the secondary maximum 
at noon; the primary minimum at 5:30 a. m. and the secondary 
minimum at 5:30 p.m. It is unnecessary to give further exam- 
ples of this character ; in general it was found that under normal 
conditions of growth, cell-division was most active an hour or 
two before midnight and about noon, and was least active about 6 
a. m. and 4 p. m. 
Curve IIT in FIGURE 2 is introduced with its accompanying 
temperature curve to illustrate a very peculiar exception to this 
general rule. Cell-division here followed a perfectly normal 
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ae 4 fle . , 
iat onal ae 
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Zt mee meat OEE Ss ces <j 
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‘ a. mM. 
FIGURE 2, Cell-division in root of 4//ium,. /, temperature. 
course until just after the period of the primary maximum. Then 
instead of falling steadily to the primary minimum, it increased 
rapidly and reached a maximum far above that shown by any 
other series, at about the time when all other series showed the 
most pronounced minimum, 7. ¢., at6.a.m. Then falling to its 
normal rate it proceeded after the typical fashion. That the 
rhythm of this plant was rendered abnormal in the prolongation of 
its most active period by some unknown conditions is evident. “N° 
other series showed any variation of this nature nor nearly of 
this extent. The curve is introduced here to show that when the 
usual rhythm of cell-division is interfered with, the normal rhythm 
