I have already shown: (1) that the diurnal movement just described is due to physiological reaction, and that the movement is abolished at the death of the plant; (2) that light has little or no effect, since the thick bark and bases of leaves screen the living tissue from the action of light; (3) that transpiration has practically no effect on the periodic movement, since such movement takes place in other plants completely immersed under water; thus _Ipomoea aquatica_, a water plant, kept under water, gave the normal diurnal curve similar to that of the palm. The modifying effect of transpiration was in this case, completely excluded. I obtained similar effect with geotropically curved stem of _Basella cordifolia_ (p. 25); (4) that the weight of the plant-organ as such, has little effect on the diurnal curve, since an inverted plant continues for a few days to exhibit the periodic movement, in spite of the antagonistic effect of weight. A different experiment will be described (see p. 582) where the effect of weight was completely neutralised and the plant-organ gave, nevertheless, the normal diurnal curve. [Illustration: FIG. 200.--Diurnal record of inclined palm tree, of geotropically curved procumbent stem of _Tropæolum_ and the dia-geotropic leaf of palm. Note general similarity between diurnal curve of plants and the thermographic record.] I have also shown that the diurnal movement is determined by the modifying influence of temperature on geotropic curvature. Rise of temperature opposes or neutralises the geotropic curvature; fall of temperature, on the other hand, accentuates it. The particular diurnal movement was not confined to the palm trees, but was exhibited by all plant-organs subjected to the stimulus of gravity. DIURNAL MOVEMENT OF PROCUMBENT STEMS AND OF LEAVES. [Illustration: FIG. 201.---Diurnal records of leaves of _Dahlia_, _Papaya_ and _Croton_.] _Experiment 210._--In order to demonstrate the continuity of the phenomenon of diurnal movement I took various stems growing in water or land for my experiment. The plants were laid horizontally, till the stems bent up and assumed the stable position of geotropic equilibrium. In figure 200 is given records of the inclined palm tree, of procumbent stem of _Tropæolum_, and the leaf of the palm tree. The very close relation between the temperature-variation and the movement of different plant-organs is sufficiently obvious. I shall next give a series of diurnal records of leaves of different plants such as those of _Dahlia_, _Papaya_ and _Croton_ (Fig. 201). In these also fall of temperature induces an up-movement while rise of temperature causes a fall of the leaf. I shall presently refer to the 'personal equation' by which the record of one plant is distinguished from another. CONTINUOUS DIURNAL RECORD FOR SUCCESSIVE THERMAL NOONS.