FRAMEWORK OF THE PLANT 275 
addition to these elements, most proteins contain a small amount 
of sulphur and some proteins also contain a small amount of 
phosphorus. By chemically combining in certain proportions 
the carbon, hydrogen, and oxygen of the sugar with the nitrogen, 
sulphur, and phosphorus obtained from the soil, proteins are 
formed, but as to how the proteins are transformed into living 
protoplasm no one knows. 
Framework of the Plant. — Protoplasm, since it is a semi- 
fluid, has no definite shape except when enclosed in a framework. 
It is by means of a frame- 
work that higher plantsare 
able tososhape themselves 
asto beadjusted tothesoil, 
air, and sunlight. 
The cell walls constitute <= 
the framework. They are 
so joined as to divide the 
plant into the compart- 
ments in which the pro- 
toplasts or individual 
masses of protoplasm re- 
side. The fact is, how- 
ever, that each cell is en- 
closed by walls of its own; 
but the adjacent walls of — yg. 248.—Cells with protoplasm shrunken, 
neighboring cells are usu- so that the fine strands of protoplasm extend- 
ally so closely joined that ing through the cell walls and connecting 
the cells appear to be sep- neighboring protoplasts may be seen. Highly 
: magnified. 
arated by a single wall. 
Through very small pores in the cell walls, the protoplasts are 
commonly connected by small protoplasmic strands, which afford 
a means of communication between the protoplasts of neighbor- 
ing cells. (Fig. 248.) 
The primary substance of which cell walls are formed is 
cellulose, a substance closely related to sugar as its formula 
(CeHiO0s)n indicates. In the formula (CsHi0s)n each combina- 
tion CsHwOs, of which an unknown (n) number are combined in 
forming cellulose, is a molecule of sugar minus a molecule of water 
as may be seen from the equation CsH.».Os — H.0 = CeH 03. 
Thus the formation of cellulose involves no other elements than 
Risen 
