TABLE XLIII.—ELECTRIC EXPLORATION OF DIFFERENT LAYERS ON THE LOWER SIDE OF THE ORGAN (Nymphæa).
| Position of probe. | Galvanometer deflection. |
| Surface | 2 divisions. |
| 0·2 mm. | 4 " |
| 0·4 " | 8 " |
| 0·6 " | 16 " |
| 0·8 " | 20 " |
| 1·0 " | 32 " |
| 1·2 " | 16 " |
| 1·4 " | 12 " |
| 1·6 " | 4 " |
| 1·8 " | 0 " |
It is thus seen that just as in the upper so also in the lower side, the electric variation undergoes at first an increase which attains a maximum; beyond this point the electric change undergoes a rapid decline. The induced electric change on the upper and lower sides are, however, different, galvanometric negativity in one case and positivity in the other.
The maximum galvanometric negativity of the upper side was found to occur at the geo-perceptive layer. We may next inquire about the anatomical characteristic of the layer in the lower side of the organ which exhibits the maximum galvanometric positivity. Microscopic section of the specimen employed in the above experiment showed the particular layer to be the starch crescent which lies above the vascular bundle. Thus the same geotropic layer which when placed above shows the maximum galvanometric negativity, exhibits maximum positivity when placed below.
METHOD OF TRANSVERSE PERFORATION.
Experiment 191.—I next carried out a complete exploration of the interior of the organ along the diameter. The probe started from the upper surface, and came out at the lower by successive steps of 0·2 mm., the corresponding geo-electric effects being observed at each step. It has to be borne in mind that the successive readings were obtained by rotation from vertical to +90° (A above); the rotation was never carried out in the negative direction through -90°. But the probe entering from above passed the central axis, and entered a region where the galvanometric indication was transformed from negative to positive. The following table gives the results obtained with the flower stalk of Nymphæa.
TABLE XLIV.—SHOWING THE INDUCED GEO-ELECTRIC DISTRIBUTION ACROSS THE FLOWER STALK OF Nymphæa (diameter = 6·8 mm.)
| Position of probe. | Galvanometer deflection. |
| Surface | - 10 divisions. |
| 0·2 mm. | - 26 " |
| 0·4 " | - 40 " |
| 0·6 " | - 50 " |
| 0·8 " | - 62 " |
| 1·0 " | - 72 " |
| 1·2 " | - 88 " |
| 1·4 " | -108 " |
| 1·6 " | - 72 " |
| 1·8 " | - 44 " |
| 2·0 " | - 30 " |
| 2·2 " | - 18 " |
| 2·4 " | - 10 " |
| 2·6 " | - 5 " |
| 2·8 " | - 2 " |
| 3·0 " | 0 " |
| 3·2 " | 0 " |
| 3·4 " | 0 " |
| 3·6 " | 0 " |
| 3·8 " | 0 " |
| 4·0 " | 0 " |
| 4·2 " | + 2 " |
| 4·4 " | + 4 " |
| 4·6 " | + 5 " |
| 4·8 " | + 11 " |
| 5·0 " | + 22 " |
| 5·2 " | + 38 " |
| 5·4 " | + 46 " |
| 5·6 " | + 39 " |
| 5·8 " | + 32 " |
| 6·0 " | + 24 " |
| 6·2 " | + 18 " |
| 6·4 " | + 12 " |
| 6·6 " | + 6 " |
| 6·8 " | + 3 " |
