ponents can no longer be considered as supplying nutritive material for the organism that lives in them.
The fact that the cells which are out of harmony with the body are dependent upon nutritive material of the most varied nature for the opportunity of extending their existence, and more particularly for maintaining their species, gives us an insight into the kind of influence exercised by these parasites on the host. In the first place they may act injuriously by the simple removal of nutritive substrates, while, in addition, the preparatory decomposition of the nutritive material may give rise to by-products which are harmful to the organism. We can well imagine that particular cells have ferments at their disposal, which decompose particular substrates in a thoroughly characteristic fashion, and so, for instance, produce stages of decomposition which are quite out of harmony with the cells of the host. The same substrate may be decomposed in the most various ways, right clown to its simplest structural units. The idea of an atypic decomposition of substances in harmony with the body, cells, and plasma, by ferments of disharmonious cells, suggests the possibility that micro-organisms, though not actually themselves passing into the circulation substances that are directly poisonous, may act injuriously, simply from the fact that, by means of fermentative decompositions, they form products out of the material
