No phenomenon of tropic movement appears so inexplicable as that of geotropism.
Thus I am now observing something about geotropism, and I had no idea a few weeks ago that this would have been necessary.
The root is thus supposed to be characterised by "positive" and the shoot by "negative" geotropism.
Hence an agent which acts on the organ from outside, induces phototropic change earlier than variation in geotropism.
geotropism is a specific subject in the physiology of plants.