plasma? Is it deprived of the possibility of defending itself against such substances, or have the cells of the body also, excluding those of the intestines, retained the capacity of attacking complicated substances which are out of harmony with the. organism, and of reducing them by profound decomposition to indifferent particles, which the cells may use for the construction of new material, or else as a source of energy?
To solve this problem, in a satisfactory manner, preliminary experiments on a very large scale were required. First of all, it was necessary to ascertain in what manner the individual cells of the body use up the nourishment which is normally brought to them by the blood. Does the individual cell decompose the complicated nutritive material directly into its end-products, or does it always disintegrate them first into simpler fragments, which are then reduced by successive stages, until finally the whole of the stored energy which the organism is capable of setting free is at the disposal of the cell, and the final products of the decomposition appear? All experiments that have hitherto been carried out in this direction lead us, as we pointed out at the beginning, to the idea that each separate cell of the body in general, with very few exceptions, disposes of the same, or of similar, ferments as those secreted by the digestive glands into the intestinal
