Finally, pathology provides us with a large number of cases supporting our view of the specific structure of the different cells belonging to a given organism. We know that certain poisons have an injurious effect only upon very definite kinds of cells. We might here refer to the well-known system diseases of the central nervous system. The so-called metasyphilitic phenomena, for instance, manifest themselves, only in very special regions of the spinal cord and the brain.
The idea that each kind of cell has its own structure, and to some extent its own metabolism, opens up a wide vista for therapy also. So far as the organism always forms products which act upon certain cells and only upon these, it must be possible to find substances which will act only upon those cells whose metabolism we may wish to alter in some way or other, or whose complete destruction is desirable. The latter is the aim of the battle waged against germs of infectious diseases and tumour cells, especially cancer. There is a great future for cell-specific therapy, which will pay special attention to the structure and the configuration of the means employed, or else attempt generally so to modify the chemical and physical conditions in certain cells that life will be impossible for them.
The admission of a certain specific structure, for each cell species with special functions, implies that each separate cell possesses special means enabling it
