The stereom is furnished either by cortical cells or by the tracheal elements, in a few cases by fibres which arc probably homologous with sievetubes.
The food so absorbed passes to the outer cortical mycellum, and from this tc the inner hyphae, which appear to be the organs of the interchangi of substance, for they are attracted to the neighborhood of thi nuclei of the cells, which they enter, and iii which they form agglom erations of interwoven filaments.
If a clean cut remains clean, the cambium and cortical tissues soon form callus over it, and in this callusregenerative tissuenew wood, &c., soon forms, and if the wound was a small one, no trace is visible after a few years.
The cortical tissues gradually shrink and dry up, turning brown and black in patches or all over, and when at length the cambium and medullary ray tissues dry up the whole twig dies off.
Latex, though chiefly secreted in vessels or small sacs which reside in the cortical tissue between the outer bark and the wood is also found in the leaves and sometimes in the roots or bulbs.