383; Ehrlich, " Mastzellen," Arch.
If the striking conceptions of Paul Ehrlich and Emil Fischer continue to prove as fertile in inspiring and directing research as at present they seem to be, another wide sphere of.
Immunity: Ehrlich, " On Immunity with Special Reference to Cell-life," Proc. R.
The technique of serum preparation has become since that time greatly elaborated and improved, the work of P. Ehrlich in this respect being specially noteworthy.
In other cases such changes cannot be detected, and the only evidence of their occurrence may be the associated symptoms. The very important work of Ehrlich on diphtheria toxin shows that in the molecule of toxin there are at least two chief atom groups - one, the " haptophorous," by which the toxin molecule is attached to the cell protoplasm; and the other the " toxophorous," which has a ferment-like action on the living molecule, producing a disturbance which results in the toxic symptoms. On this theory, susceptibility to a toxin will imply both a chemical affinity of certain tissues for the toxin molecule and also sensitiveness to its actions, and, furthermore, non-susceptibility may result from the absence of either of these two properties.
Anti-substances may be arranged, as has been done by Ehrlich, into three main groups.
The latter view, first advocated by Ehrlich, harmonizes with the facts established with regard to toxic action and the behaviour of antitoxins, and may now be regarded as established.
This result, which is usually known now as the " Ehrlich phenomenon," was explained by him on the supposition that the " toxin " does not represent molecules which are all the same, but contains molecules of different degrees of combining affinity and of toxic action.
It is strongly supported by Ehrlich, who, in his so-called " side-chain " (Seitenkette) theory, explains antitoxin production as an instance of regeneration after loss.
The former (Immunko y per of Ehrlich, substance sensibilisatrice of Bordet) is the more stable, resisting a temperature of 60° C., and though giving the specific character to the reaction cannot act alone.
Red corpuscles (Bordet, Ehrlich and Morgenroth), leucocytes and spermatozoa (Metchnikoff).
The most important works on immunity are: Ehrlich, Studies in Immunity (English translation, New York, 5906), and Metchnikoff, Immunity in Infective Diseases (English translation, Cambridge, 1905).