TOXINS 127 



of time produce an almost indetiiiite amount of effect, whereas toxins 

 act more nearly quantitatively. It seems as if the enzyme were bound 

 to the body upon which it acts, as is the toxin, but that after it has 

 destroyed this body it is set free in a still active form, ready to ac- 

 complish further work, whereas the toxin is either not set free, or it 

 becomes inactive after it has once ])een combined. 



Agencies Destroying or Modifying Toxins. — Toxins are very sus- 

 ceptible to li^lit. direct suidi^ht soon destroying the power of toxin 

 solutions. Fluorescent sul)stances destroy toxins both in vitro and 

 in the body.^'' Oxygen, even dilute as in air, is harmful ; and all 

 oxidizing agents, including oxidizing enzymes, destroy them quickly."'' 

 Like enzymes, they withstand such antiseptics as chloroform, toluene, 

 etc., and are precipitated by the heavy metals. Some agencies seem 

 to attack only the toxophore portion of the molecule, e. g., iodin, car- 

 bon disulphid (Ehrlich). Certain toxins (diphtheria, dysentery) 

 can be converted into non-toxic modifications by acids, the original 

 toxicity being restored by bases (Doerr),-'^ which fact, Pick maintains, 

 is in support of the protein nature of toxins. Salts of monovalent 

 metals have no effect on toxins, but bivalent and trivalent salts are 

 injurious to them, tetanus toxin being more sensitive than diphtheria 

 toxin. X-rays are said to weaken them."- 



Introduced into the gastro-intestinal tract, most bacterial toxins 

 are not absorbed (botulinus toxin excepted), cause no symptoms, and 

 do not reappear in the feces; they are therefore destroyed by the 

 contents of the tract, pepsin, pancreatic juice, and bile all being capa- 

 ble of destroying toxins."^ They may, however, when injected sub- 

 cutaneously, circulate unimpaired in the blood of non-susceptible an- 

 imals, gradually disappearing, more through slow processes of de- 

 struction than hy elimination. When injected into susceptible ani- 

 mals, they soon disappear from the blood, being fixed in the organs 

 that they attack. Toxins are also bound hy lipoids, fats and similar 

 substances, which accounts, at least in part, for the affinity of tetanus 

 toxin for nervous tissues."* In common with other colloids they are 

 adsorbed by surfaces, such as charcoal, kaolin, etc. ; such adsorption 

 is accompanied by little change in any of the physical properties of 

 the solution, except an increase in surface tension (Zunz). 



Differences from Ptomains. — While ptomains are formed by cleav- 



89 Literature given by Xoguchi. .Jour. Exper. ^led., 11)06 (8), 263. 



'■'0 According to Pitini (Biochem. Zeit.. 1910 (2o), 2.57) toxins cause their liarm- 

 ful effects by reducing tlie oxidizing capacity of the tissues. 



91 Wien. klin. Woch., 1907 (20), 5. 



92Gerhartz, Berl. klin. Woch., 1909 (46), 1800. 



93 Baldwin and Levene (.Jour. Med. Research, 1901 (6), 120) found that diph- 

 theria and tetanus toxin are both destroyed, apparently tiirougli digestion, by 

 pepsin, trypsin and papain acting for several days. Review of Literature bv 

 Lust, Hofmeister's .Beitr., 1904 (6), 1.32. See Vincent, Ann. Inst. Pasteur, 1908 

 (22), 341. 



94Loewe, Biochem. Zeit., 1911 (33), 225, and (34), 495. 



