SPECIAL PROPERTIES OF THE PRINCIPAL TOXINS 113 



example, tetanus toxin contains tetanospasmin, that has a special 

 affinity for nervous tissue; and tetanolysin, a poison that has a 

 selective affinity for erythrocytes and is hemotoxic. Ehrlich has shown 

 that these are really different toxins, and not one toxin with a two-fold 

 function, even the antitoxins of the two being different. Similarly, the 

 general symptoms and necroses of diphtheria are attributed to the main 

 toxin of the bacillus, and the nerve lesions and paralyses to a secondary 

 but distinct secretory product known as toxon. This latter view of 

 Ehrlich's, however, is much disputed, many investigators believing that 

 toxon represents a degenerated or modified form of the one toxin. 



The special affinities of toxins for certain tissues have analogies 

 among the poisons of higher plant life, as, for example, strychnin has a 

 similar selective affinity and is said to be specific in its action upon the 

 motor cells. 



The venom of various serpents, especially that of the cobra, has 

 specific action: the erythrocytes of various animals are readily attacked 

 by it, and the cells of the respiratory center are apparently profoundly 

 affected. 



Aside from the special effects of the toxins upon certain cells and 

 tissues, it must be remembered that toxins may involve the body-cells 

 in general, and particularly those of the parenchymatous organs, such 

 as the kidneys, heart, and liver, causing coagulation of the protoplasm 

 (cloudy swelling) and final dissolution. The harm brought about by 

 the toxins or toxic products of the pyogenic group of microorganisms, 

 for instance, acts mainly in this manner. 



SPECIAL PROPERTIES OF THE PRINCIPAL TOXINS 

 1. Diphtheria Toxin. Diphtheria bacilli vary considerably, both in 

 tissues and in artificial culture media, in the quantity of toxin se- 

 creted; thus in bouillon large amounts are seldom found in less than 

 from seven to fourteen days. 



The action of the toxin is dependent upon the dosage, and a certain 

 period of time must always elapse before the symptoms appear, the 

 minimum being about one day. Large doses may shorten this period 

 of incubation, but cannot diminish it below a certain limit. 



The lesion of diphtheria is practically always local, and is usually 

 situated on the mucous membrane of the upper air-passages. It is 

 characterized by the formation of a pearly white membrane that is 

 adherent to the underlying edematous tissues. The toxin produces 

 necrosis of the surface epithelium, and the product, together with fibrin 



