132 CELLS AND TISSUES 
which spread into the soil where they take up water by means 
of osmosis, are the chief absorptive structures. (Fig. 119.) There 
are some plants, however, which live on other plants, in which 
case the root tissues absorb directly from the tissues with which 
they are in contact. In some cases the leaves absorb, as in 
the Sundew (Drosera), Venus’s Flytrap (Dionea muscipula), 
and Pitcher Plants (Sarracenia), where the eaves are especially 
constructed for catching and absorbing insects. 
Food-making Tissues. — The principal food-making organs are 
the leaves where the cells are provided with chloroplasts and so 
arranged that they can obtain the raw materials from which foods 
Fic. 120. — Cross section of the leaf. jf, food-making tissue; e, epidermis; 
v, cross section of a vein. 
are made. (Fig. 120.) However, food-manufacture is not lm- 
ited to leaves, for all green stems have just under their epidermis 
a band of green cells, known as the cortex, in which food is manu- 
factured as long as light and air are not excluded. (Fig. 117.) 
Storage Tissues. —— Any living cell usually contains some 
stored food, but there are cells which have food storage as their 
chief function. This is true in the endosperm and fleshy cotyle- 
dons of seeds, and in Irish Potatoes, Sweet Potatoes, and in other 
tubers and roots where the cells enlarge and become packed with 
food. In the pith some water is usually stored and often much 
food, as is well known in the case of Sugar Cane and Sorghum in 
which the pith contains much sugar. Throughout the wood of 
trees there are thin-walled living cells, forming the medullary rays, 
which function as a storage tissue. In Maple trees the sugar 
occurring in the spring sap comes from the starch which was 
