The physical part of the dog’s immune system extends from the subcellular level to the whole organism. Each and every cell and all organ systems have their own components of immunity, and in turn, each has some sort of independent, inner regulator. Modern physics has taught us that the nature of any system cannot be discovered by dividing it into its component parts and studying each part by itself. We must keep our attention fixed on the whole and on the interconnection between the parts. The whole is never equal simply to the sum of its various parts.
