ON THE NATURE OF TOXINS 47 



temperature approaching that of the body, it follows that the hapto- 

 phore group can functionate at a low temperature (o to 10 C.), 

 while the toxophore group can only do so at a fairly high one. 

 Looked at in this way, the process of intoxication with an endo- 

 toxin, or of haemolysis with a bacterial haemolysin, may be divided 

 into two stages : in the first place, the haptophore group of the 

 toxin or haemolysin combines with the protoplasm or with the 

 stroma of the red corpuscle, and in the second the toxophore 

 group exerts its action, and the cell is poisoned or the red corpuscle 

 dissolved. The phenomena of tetanus in frogs is thus readily 

 explicable. 



We shall see several other examples of substances in which it 

 is possible to distinguish between a combining and an active 

 group, and the same terminology will be adopted throughout 

 (agglutinoids, complementoids, etc.). 



The change of toxin into toxoid takes place in all exotoxins, 

 but at very different rapidities. Tetanolysin is transformed com- 

 pletely into haemolysoid in a day or so, whilst tetanospasmin, the 

 true toxin of the disease, is much more stable. The process is 

 accelerated by heat, light, and the access of oxygen, and by 

 certain chemical substances which are not sufficiently powerful 

 to destroy the toxin outright. Of these the most important are 

 a solution of iodine in iodide of potassium, and bisulphide of 

 carbon. 



The exotoxins are destroyed outright by heating to the boiling- 

 point (to this rule there are a few exceptions, none of which has 

 been fully examined), by strong acids and alkalis, and by the 

 action of the digestive enzymes. They are, as a rule, precipitated 

 by the substances which precipitate proteids, and destroyed by 

 the substances that destroy those bodies. They have, further, 

 the power of attaching themselves to precipitates, of whatever 

 nature, which are thrown down in fluids containing them ; so that 

 formerly they were thought to be albumins, albumoses, nucleo- 

 albumins, etc., since they were carried down mechanically when 

 these substances were precipitated from a bacterial culture in 

 which they were present along with the exotoxin. In these points 

 again they closely resemble the enzymes. 



They are substances the molecules of which must be small in 

 comparison with those of the coagulable proteids, since they 

 readily pass through filters (of unglazed porcelain permeated with 

 gelatin) which retain the latter. This fact was put to an ingenious 



