538 COLLECTED STUDIES IN IMMUNITY. 



(b) " Certain animals non-susceptible to certain toxins never- 

 theless produce antibodies " needs no further explanation according 

 to my theory. Certain species of animals may possess suitable 

 receptors for binding the toxin and producing antitoxin although 

 their cells are insensitive to the action of the toxophore group. Accord- 

 ing to Metchnikoff this seems often to be the case with tetanus toxin 

 in crocodiles. As already pointed out years ago by Weigert l accord- 

 ing to my theory, the production of antitoxin need not at all be 

 preceded by any injury in a clinical sense. In fact, too strong an 

 injury may cause the cell to lose its power of regeneration, owing 

 to the toxic action on the vital group [Leistungskern]. For example, 

 if a specific nerve poison is anchored by a fitting receptor of an indiffer- 

 ent cell (liver) we should expect the production of an antibody by 

 the liver, even if the liver-cell does not become tetanized. In my 

 address at Hamburg 2 before the Congress of Naturalists I pointed 

 out that the local origin of antitoxin, which Romer deduces from 

 his splendid experiments with abrin, will often make it possible to 

 transfer part of the antitoxin production from the vital organs to 

 the indifferent connective tissue, by means of subcutaneous injec- 

 tion of poison. 



Gruber's next statement is: 



(c) " Despite a plentiful production of antibody, the suscep- 

 tibility to the poison may remain, or even increase." 



I have already discussed the principle of hypersensitiveness 

 and mentioned the fact that this objection restrained me for a long 

 time from publishing my theory. But even these phenomena were 

 satisfactorily explained in accordance with the side-chain theory, 

 by the assumption of an increase of affinity and a rupture of the 

 toxin-antitoxin combination. To be sure it is possible that our 

 explanation touches but part of the subject, and that in reality the 

 phenomena are far more complex. But this is no reason for seek- 

 ing to overthrow the theory; to do so would be to completely mis- 

 apprehend the purpose of a theory. Surely one cannot demand 

 that a theory will at once explain all the complex phenomena of 

 so difficult a subject as this. A theory ought primarily to possess 

 heuristic value, pointing out new paths into a complex subject; it 

 should smooth the way. The actual research must be left to the 

 scientific investigator. Science can be advanced only by means 



1 I. c. * Deutsche med. Wochenschr. 1901. 



