他的观点是，在某种程度上二者均由运输物质的网络构成——公路，铁路，水路以及煤气管，污水管还有电缆线都在输送物质，动物血管和植物运输汁液的木质部、韧皮部也是如此。
Roads, railways, water and gas mains, sewage pipes and electricity cables all move things around. So do the blood vessels of animals and the sap-carrying xylem and phloem of plants.
专门用来运输矿物元素的系统称为木质部。
A system confined to the transport of mineral elements is known as the xylem.
在老茎中，仅最新的木质部环参与物质的运输。这些木质部环组成边材。
In older stems, only the most recent rings of xylem participate in the transport of materials. these make up the sapwood.
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