VENOMS, TOXINS, ANTIBODIES 347 



in vitro was used as a measure of its activity. He attributes the protec- 

 tion to the formation of inactive complexes of dye and protein molecules. 

 The paper deals also with protection of many test objects besides ricin 

 and is primarily a contribution to the theory of the photodynamic effect. 



Baroni and Jonesco-Mihaiesti (13) also found rather rapid loss of 

 agglutinating power by ricin upon ultra-violet irradiation. Relative 

 rates of destruction are given by these authors for various toxins, etc., 

 but can hardly be granted quantitative significance, for reasons discussed 

 below. 



The upper wave-length limit for effective photochemical ricin inactiva- 

 tion, as judged by its toxicity for test animals, was shown by Carmichael 

 to lie at about 2450 to 2540 A (32). 



Schubert (142) exposed ricin, either dry or in 0.01 per cent aqueous 

 solution, to the near ultra-violet (" Originalhohensonne " lamp with 

 uviol glass screen) and observed that it lost its toxicity for white mice. 

 Welch (162) showed that its toxic and agglutinating powers were 

 destroyed at about the same rate by ultra-violet radiation, but that its 

 antigenic power was more resistant. 



BACTERIAL TOXINS 



These appear usually to be proteins or products of protein decomposi- 

 tion, and those produced by different organisms differ in the characteristic 

 symptoms produced. Those whose photolability have been studied are 

 all exotoxins, i.e., products given off to the culture medium by the growing 

 organisms; they are usually broth filtrates, or, in one case (hemotoxin of 

 B. proteus), broth cultures which have been killed by ether. 



Diphtheria toxin was the first of all the substances treated in this 

 paper to be studied from the point of view of its resistance to irradia- 

 tion. Roux and Yersin (138), in 1889, published the significant observa- 

 tion that although quite stabile in the dark, it was almost completely 

 inactivated by 10 hr. exposure to sunlight. When sealed up in small 

 tubes without air, the toxin was only slightly injured by similar irradia- 

 tion. The authors conclude that visible light plus oxygen is the active 

 agency. 



Emmerling (51) compared the effects of sunlight on diphtheria toxin 

 and various enzymes, finding the toxin to be less stabile than the enzymes. 

 Aside from this, his work serves merely to confirm that of Roux and 

 Yersin. 



Photodynamic destruction of diphtheria toxin in the presence of 

 eosin (0.05 per cent) by 3 days' exposure to diffuse daylight has been 

 observed by Tappeiner and Jodlbauer (155). Similar effects were 

 observed with fluorescein (0.1 per cent), methylene blue (0.02 per cent), 

 and dichloranthracene disulfonate. Rabbit or ox gall may also be used 



