NUTRITION 393 
lated to one another in amount as to form what animal feeders call 
a balanced ration. This is shown by the fact that, when growth is 
resumed, food of one sort is not used in the ratio which it bears 
to others stored with it. Often indeed the reserves are not exhausted 
until the plant or shoot, having begun independent manufacture, is able 
to supplement the deficiencies in the stored ration. Thus, finally, it 
may utilize all the accumulated reserve, but often this is not done, and 
the excess is again stored elsewhere. 
Traveling forms. Since the places of storage are seldom the places 
of food making or use, translocation of food usually precedes and fol- 
lows storage. Unfortunately, little is known about the translocation 
of foods. It seems clear that the traveling forms must be relatively 
simpler than those in which they are stored. Obviously, they can travel 
only in solution, and, as a rule, the protoplasm does not permit the pas- 
sage of the foods in their storage forms. Thus, cane sugar probably 
travels as glucose and fructose; the fats as glycerin and fatty acids; 
the proteins as amides. For in all translocation of foods, whether in 
small plants or large, it is necessary that they be able finally to diffuse 
through live cells, and the more complex compounds are usually un- 
able to do this. 
Diffusion. In the smaller plants osmotic differences alone must 
account for the transfer from cell to cell. This may be facilitated by 
the delicate protoplasmic connections which commonly exist and would 
make it unnecessary for all the food to pass through the cell wall itself. 
In fungi which have coenocytic hyphae, the absence of transverse parti- 
tions probably facilitates transfer ; while the surging movements that 
have been observed in the contents of certain molds (Mucorales) would 
certainly do so. Yet actual knowledge regarding the translocation of 
food in even the simplest plant is scanty. Food obviously gets from 
place to place, and there is apparently no way for it to do so except by 
diffusion. 
Conducting system. In the larger plants a conducting system is 
developed; and it is evidently advantageous that the slower movement 
of diffusion be supplemented by a more rapid one along the chief lines 
of travel when the factories are separated by considerable distances from 
the places of use or storage. This conducting system in all the vascular 
plants consists of the phloem strands. It may be supplemented in 
certain large families by the latex system, though the function of the latex 
is somewhat uncertain. 
