52 BOTANY. 
stems of our woody trees there is but very little of the fun- 
damental system present, making up the very small pith and 
the thin plates (medullary rays) running radially through 
wood and bark. 
95. In its fullest development the fundamental system 
may contain soft tissue (parenchyma) of various forms, 
thick-angled tissue, stony tissue, fibrous tissue, and milk- 
tissue. Their arrangement, within certain limits, presents 
a considerable degree of similarity in nearly related groups 
of plants, but this is by no means as marked as in the case 
of the fibro-vascular system. 
96. (1) Soft tissue (parenchyma) is the most constant of 
the fundamental tissues; it makes up the whole of the in- 
terior plant-body in those plants where there has been no 
differentiation into more than one tissue, and it is present 
in varying amounts in all plants up to and including the 
highest. 
97. (2) Thick-angled tissue (collenchyma) when present, 
as it generally is in the stems and leaves of flowering 
plants, is always either in contact with or near to the epi- 
dermis. : 
98. (3) Stony tissue (sclerenchyma) is common beneath 
the epidermis of the stems and leaves of flowering plants and 
ferns, and the stems of mosses. It sometimes appears to 
replace thick-angled tissue. Some elongated forms of stony 
tissue are scarcely to be distinguished from fibrous tissue.- 
99. (4) Fibrous tissue occurs in some leaves and stems 
near to the epidermis. In ferns it forms thick band-like 
masses, giving strength torthe stems. 
100. (5) Milk-tissue (laticiferous) may occur, apparently, 
in any portion of the fundamental system of flowering 
plants, 
