defensive measures adopted depend on their nature. In another case two individuals throw themselves brutally one upon the other without any previous choice of weapons; then any means is good, if it only succeeds in overcoming the opponent somehow.
One fact must always be kept in mind. When we introduce proteins or peptones and the like into the blood-vessels, these are never pure compounds. Together with the peptones we certainly introduce into the circulation a number of different stages of the decomposition of proteins. Suppose we take the white of an egg, then without doubt innumerable albuminous substances are present, which greatly differ one from the other. We must not forget the fact, that traces of particular substances are quite sufficient to cause the formation of ferments. The cells, on the contrary, set free substances that are probably of a very precise character.
If we artificially introduce material that is out of harmony with the blood, the animal organism reacts against it with a whole complex of defensive ferments, because our material is always a mixture of substances. It is to a certain degree prepared for all eventualities. It has no actual knowledge of the characteristics of the introduced product. If, at any point, particular cells exhibit a deficiency of function in respect of their metabolism, then there always appears in the blood plasma, from one moment to
