KELLICOTT: PERIODICITY IN ROOT OF ALLIUM 541 
six hours; at 7:30 p. m,. the roots were replaced in tap-water. 
Examination of the tips gave the results tabulated as curve /, F1G- 
URE 5. At the time the roots were placed in the solution, cell- 
division was proceeding at about the usual rate for those tips 
similarly placed in water. After removal to the solution, however, 
cell-division decreased very rapidly. After replacing in water, 
cell-division recommenced and after a period of two hours we find 
the rate of mitosis gradually increasing until five hours after 
removal from the solution the rate was above the normal for roots 
placed in water, or about like those placed in glucose. Unfortu- 
nately the number of tips on this bulb was exhausted at this time 
and no further observation was possible. 
(@) Peptone.— As a non-crystallizable, nutrient solution, a 25. 
per cent. solution of peptone in tap-water was used. As before, 
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t det Y hal 20 
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Ficure 5. Elongation of root of 4//ium immersed in 2 per cent. MgCl, (7), and 
in 2.5 per cent. peptone (//). ¢, temperature. 
roots were removed from sand to water at 10a.m. At 2:30 p. 
m. they were transferred to the peptone solution and examined at 
intervals during a period of thirty hours. The rate of mitosis in 
these tips is shown graphically in curve //, FIGURE 5. In general 
it is very similar to the curves of tips in water and glucose, espe- 
cially during its later course. In its earlier portion it lacks the 
Pause or rise just before midnight. Cell-division almost stopped 
after 16-20 hours in the solution. 
As already stated the general result of placing growing roots 
in liquids or solutions is to decrease the rate of cell-division and to 
