KELLICOoTT : PERIODICITY IN ROOT OF ALLIUM 549 
and the maxima day and night; the relative intensities of the 
maxima and minima were inconstant even in the same plant. 
This is apparently the only recorded instance of a double daily 
wave of growth in an aérial part, of such a nature as is found in 
the root. 
6. Relation between cell-division and elongation 
The actual relation in time between cell-division and elonga- 
tion can be seen most easily by reference to FIGURE 8, where there 
are composite curves of all my records of normal cell-division and 
elongation reduced to similar proportions. It is at once evident 
that the rhythms agree in time but always occur in opposite direc- 
cian os 
SECA 
UNTACCLIAL A 
Sractnae 
NICER LY 
i Rie 
eer RsCs, 
ee! & 
| Ciy 
| argoorars BESS ares 
Jt 
| Pp. m. a. M1. 
. Ficure 8. Composite curves of cell-division (/) and elongation (//). 
tions, 7. ¢. when elongation is at a maximum cell-division is at a 
minimum and vice versa. The primary maximum of cell-division 
Corresponds perfectly with the primary minimum of elongation at 
itp. m. The primary maximum of elongation corresponds with 
the secondary minimum of cell-division about 5 p. m., while the 
Primary minimum of cell-division occurs at the time of the sec- 
ondary maximum of elongation at 5 a.m. In general, through- 
oat the curves have opposite directions. The only rea] excep- 
tion occurs between 3 and 7a. m. when, as already noted, the 
decreasing rate of elongation can hardly be considered a constant 
