this way a cell dies, though it be plentifully surrounded by a material rich in energy, which, however, cannot be used because it lacks the proper form—both structural and configurative. It does not suit the organization of the cell. There is an abundance of oxygen at its disposal, but the latter cannot find any point of attack; and so the necessary preparation is wanting.
Some of the substances cannot be absorbed by the cell, simply because they are physically too coarse to penetrate through the cell wall. Such is the case with many colloidal substances, which must be first decomposed into simpler groups before they can pass into the interior of the cell. In these cases the presence of ferments is essential, and they have to be of such a kind as to be capable of decomposing the complicated molecules into a form which may easily penetrate through the cell wall. Often, however, such conditions may suffice as enable the coarse complex substance to be simply broken up into finer particles, which may be ingested in this form by the cell, without any molecular decomposition being necessary. Further decomposition takes place during absorption or, even later, at a suitable point within the cell.
Even a unicellular organism does not enter into intimate relations with substances which have not previously been remodelled. This remodelling
