stylistic:style_transfer, quality:corruption, linguistic:translation, quality:correction, structural:reformatting
Evidence

Various evidence supports the hypothesis. Firstly, there is an excretion of solution from the phloem when the stem is cut or punctured by the stylet of an aphid, indicating that the phloem sap is under pressure. Secondly, concentration gradients of organic solutes are proven to be present between the sink and the source. Additionally, when viruses or growth chemicals are applied to an actively photosynthesising leaf, they are translocated downwards to the roots. When applied to shaded leaves, such downward translocation of chemicals does not occur, showing that diffusion is not a possible process involved in translocation.