TOXfxs 125 



fouud that choline injected directly into the cortex or under tlie dura 

 is extremely toxic, causing severe tonic and clonic convulsions, and 

 believes that choline may be responsible for epileptic convulsions. 

 This view has been opposed, and properly so, by Handelsmann "^ and 

 others. The attempt to ascribe importance to choline as a cause of 

 cither toxic or therapeutic effect of j"-rays seems also to be entitled to 

 but slight consideration.*- It is probably a factor in the lowering of 

 blood pressure which results from injection of extracts of various tis- 

 sues, in which it is commonly present in minute amounts,-' for very 

 minute amounts of choline will produce a decided fall in blood pres- 

 sures^ 



The Pressor Bases. — By decarboxylation of amino acids, amines 

 are obtained, and some of them, notably those derived from leucine, 

 tyrosine, phenylalanine and liistidine, have a marked effect on non- 

 striated muscle. These are discussed in Chapter xix. 



TOXINS 



Certain bacteria produce soluble poisons by sj'nthetic processes, 

 which poisons are secreted into the surrounding medium and repre- 

 sent the chief poisonous products of the bacteria, being capable of 

 causing most or all of the symptoms attributed to infection by the 

 specific bacteria that have manufactured them. To this class of solu- 

 ble poisons the term toxin has now become limited (for reasons that 

 will be mentioned below), including not only toxins of bacterial ori- 

 gin, but also poisons of similar nature produced by animals (snake 

 venoms, eel serum, etc.) and by plants (ricin, abrin, crotin). The 

 chief bacteria secreting true toxins are B. diphtherke, B. tetani, B. 

 ■pyocyaneus, and B. hotulimis (not including bacteria producing hem- 

 olytic substances resembling toxins). It will be seen that the tenn 

 toxin has been greatly narrowed since the time when all ptomai'ns 

 and other poisonous bacterial products were called toxins, until now 

 it ha.s come to include the specific poisons of but four of the great 

 group of pathogenic bacteria.*^ 



Chemical Properties of Toxins. — The chemical nature of the 

 toxins is entirely unknown. Hy various precipitation methods they 

 may be carried down, but included with them are masses of impuri- 

 ties, chiefly proteins. They behave like electro-positive colloids,®^ but 



siZeit. f. physiol. Chem., 1003 (39), 526; also see Mcd« Xews, 100.5 (86), 107, 

 for literature and methods of analysis. 



82 See Schenk. Deut. med. Woch.', 1910 (36), 1130. 



83 Schwarz and Lederer, Pfliiger's Arch., 1008 (124), 3.)3 ; Kinosliita, ihi<l.. lOlO 

 (1.32), 607. 



S4 Mendel et al., Jour. Pharm. and Fxp. Ther.. 1012 (3), 64S : Hunt and 

 Taveaii, Bulletin 73, Hyg. Lab. U. S. P. H. Service. 



85 It is possible that, dysentery bacilli, and perhaps a few other patliogens. 

 secrete a small amount of true toxin. Pick considers the active constituent of 

 tuberculin to be a true toxin, or closely related tliereto. 



SG Field and Teague, Jour. Exper. Med., 1007 (0), 86. 



