224 Professor Sranto Arrlieirius [June 9, 



action, and the corresponding property of different preparations of 

 poison tells very mnch in favour of the opinion that the blood- 

 poison and the nerve-poison are identical as well as their antibodies. 



This question is very nearly related to another, namely, the weaken- 

 ing of poisons with time. In this case we very often find that 

 the poison retains its effect of neutralizing antitoxin undiminished, 

 whereas its toxicity weakens. This question has been investigated 

 very accurately for tetanolysin and diphtheria poison, l)ecause this 

 property plays a very great part in practice. Thus, for instance, a 

 diphtheria-toxin prepared in the Danisli State Serum Institute in 

 February, 1902, slowly lost its toxicity, so thtit it was only half as 

 great in September, 190S, as when it was freshly prepared. Still its 

 power of neutralizing antitoxin remained wholly intact, and the 

 constant in the equihbrium formula did not change. This peculiar 

 behaviour was explained by Ehrlich in the following manner. The 

 molecule of the toxin is very complicated and contains one "side- 

 chain " (this term is taken from organic chemistry), which has 

 toxic properties — or, as it is said, contains the toxophorous group 

 — whereas another side-chain binds the antitoxin. With time the 

 toxophorous group decomposes, but the other, so-called hapto- 

 phorous (from Greek, haptein, bind) group, remains unchanged. 

 The product, called syntoxoid, possesses all the properties of the toxin 

 except that it is innocuous. It has, for instance, the very vahiable 

 property of provoking the production of antitoxin when injected in 

 the veins of an animal. The toxicity may be weakened artificially 

 without influencing the binding property, and this circumstance has 

 been much used in preparing antitoxins. 



A much more simple explanation is to suppose that there is 

 formed some antisensibilisator in the diphtheria-poison ; this pre- 

 paration contains a great many foreign organic substances which 

 may slowly give new compounds. This antisensibilisator diminishes 

 the action of the diphtheria poison on the nerves, but not on the 

 animal organs — it has been supposed the spleen or the bone-marrow 

 — which produce antitoxin. Further, it does not interfere with the 

 chemical reaction of toxin and antitoxin. 



In this manner the extremely complicated hypothesis of Ehrlich, 

 who assumed the presence of about ten different toxic and innocuous 

 substances (the latter called toxo'ides or toxones) in diphtheria-poison 

 (and even in other poisons), is absolutely unnecessary as regards the 

 syntoxo'ids. Many of these "partial poisons " have been introduced 

 to explain experimental errors, which were, especially at first, un- 

 usually great in this field ; another set seek to explain the successively 

 diminisln'ng neutralizing power of antitoxin, which depends upon the 

 incompleteness of its chemical reaction with toxin. As a matter of 

 fact, the "side-chain theory" of Ehrlich gives no explanation of 

 the ol)served phenomena, and has only a very moderate scientific 

 value. 



