68 
TABLE III. 
Omnilateral fore-illumination. 
Energy of - > = 
unilateral after- 12.1 M.C. during 180 secs. 25 M.C. during 100 secs. 
illumination ‘3 Eve. 
inMC.S. | Energy | Energy | | Energy | Energy 
| to front | to back | Reaction. | to front | to back | Reaction. 
inM.C.S. in M.C S. in.M. CS; in M: CS: 
44 1405 1372 0 1606 1573 0 
60 1421 1376 0° 1622 1571 0 
120 1481 1391 a 1682 1592 0 
500 1861 | = 1486 (3 2062 1687 v4 
1000 2562 1812 js 
| | 
Explanation: 
The energy to the front, 1405 M.C.S., is ie ais 5 
calculated from rae 6) Er (12.1 x le ns Bs 44) Boos!) 
b 
that to the back, 1372 M.C.S, from (+) = (12.1 x 1802 +11) MGs 
Arisz means by the sign? that “some plants give a feeble positive 
curvature, but there are always a few which curve negatively”; this 
has been confirmed by clinostat experiments. He directly connects 
this phenomenon of ‘increased sensitiveness to the negative reaction” 
with the fact, that after 300—600 M.C.S. the strength of the maximal 
curvature diminishes, and considers it possible that “by combining 
a quantity of light, which gives a curvature in excess of the greatest 
maximal strength, with a quantity which is maximal or nearly so, 
a curvature is obtainable towards the weaker illumination’. We may 
not connect the “decreased sensitiveness to the positive reaction” with 
the tendency to curve in the opposite direction and as little may we here 
directly connect the “increased sensitiveness to the negative reaction” 
with the strength of the maximal curvature, but must explain it from 
the course of the growth retardation curve. For the maximal curvature 
will be strongest in that case, where the difference between the 
ordinates belonging to rq and +2, is a maximum. The decrease in 
the amount of this difference is primarily connected with the decrease 
in slope of the growth retardation curve and it is only the rate at 
which the curvature diminishes at higher amounts of energy or the 
change to a negative curvature, which is connected with the question 
whether or no the growth retardation curve presents a maximum. 
The growth retardation curve will therefore continue to rise, although 
the intensity of curvature (i.e. the difference between the ordinates 
belonging to za and }.,) is already declining; the maximum will 
