KeELiicorr: PERIODICITY IN ROOT OF ALLIUM 539 
is rather an interruption in its rapid descent. After midnight there 
is continued descent until about noon when the curve ascends 
again to a maximum at 6 p. m. This maximum would have 
occurred normally at noon—just at the time when the ascent 
actually commenced. After the maximum at 6 p. m., which is 
the normal time for a minimal point, the curve falls again and was 
falling when observations ceased at 10:30 p. m. 
The effect of removing the roots to water was at first a stimu- 
lation resulting in very rapid cell-division for a short time. This 
was followed by inhibition of cell-division and delay of its normal 
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ig 28 oe a use 
DOS FB EE Ee Ee ge Se OE I Oe 
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Ficure 4. Elongation of root of A//ium immersed in water (/), and in 4.2 per 
Sent. glucose (77). 4, temperature. 
rhythms, “The total number of dividing cells was very consider- 
ably reduced ; the minimum which occurs normally about 6 a. m. 
was delayed until nearly noon, and the maximum which occurs 
normally at noon was delayed until 6 p.m. The inhibition of 
cell-division finally passed away partially and thirty-two hours after 
ing placed in water (7. ¢., at 6 p. m.) cell-division was again 
fairly rapid. Observations not included in the diagram were made 
TO. a.m. on the two days following the last observation charted. 
These observations showed cell-division to be fairly active, the 
Numbers of dividing cells being about 75-80 per cent. of the 
