The probable explanation is that an antitoxin is developed within them.
Supra) it might be that 12 5 doses would need to be added to the same amount of antitoxin before the mixture produced a fatal result when it was injected.
It has, moreover, been found that the serum of various animals has a certain amount of antitoxic action, and thus the basis for antitoxin production, according to Ehrlich's theory, is afforded.
The unit of antitoxin in Ehrlich's new standard is the amount requisite to antagonize i oo times the minimum lethal dose of a particular toxin to a guinea-pig of 250 grm.
In antitoxin production this combination takes place, though not in sufficient amount to produce serious toxic symptoms. It is further supposed that the combination being of somewhat firm character, the side-chains thus combined are lost for the purposes of the cell and are therefore thrown off.
Toxins may thus become so closely keyed into their corresponding atom groups, as for instance in tetanus, that they are no longer free to combine with the antitoxin; or, again, an antitoxin injected before a toxin may anticipate it and, preventing its mischievous adhesion, dismiss it for excretion.
One other important fact in support of what has been stated is that a toxin may have its toxic action diminished, and may still require the same amount of antitoxin as previously for neutralization.
Lastly it may be mentioned that when a toxin has some action which can be demonstrated in a test-tube experiment, for example, a dissolving action on red corpuscles, this action may be annulled by previously adding the antitoxin to toxin; in such a case the intervention of the living tissues is excluded.
Kanthack and Cobbett, that in certain instances the toxin can be made to pass through a gelatine membrane, whereas the antitoxin cannot, its molecules being of larger size.
The development of the immune body with specific combining affinity thus presents an analogy to antitoxin production, the difference being that in lysogenesis another substance is necessary to complete the process.