VENOMS, TOXINS, ANTIBODIES 349 



Controls in a hydrogen atmosphere or in the dark were practically 

 uninjured. Less transparent media such as gelatin served to protect 

 the toxin more or less. 



Kitasato (97) obtained more rapid detoxication of bouillon filtrates 

 by diffuse daylight than the earlier work suggested. The data, based on 

 two mice per sample, are only roughly quantitative. 



Fermi and Celh (56) found dry tetanus toxin to be completely inac- 

 tivated by 48 hr. exposure to direct sunHght, as compared with the 

 enzymes trypsin and pepsin which were not, but they believed that the 

 relatively high temperatures (40° to 50°C.) incident to irradiation were 

 responsible. If the temperature was kept at 37° or below, there was no 

 destruction of the toxin in 15 hr. At first glance this would seem to 

 invalidate Kitasato's work in which, with temperatures of 35° to 43°, 

 sunhght completely inactivated tetanus toxin in 15 to 18 hr. But it is 

 apparently the use of dried toxin rather than toxic bouillon filtrates 

 which makes the difference. Fermi and Pernossi (57) investigated both 

 and found that at temperatures not exceeding 37° the dissolved toxin was 

 completely inactivated by direct sunhght in 15 hr., in agreement with 

 Kitasato, while the dried toxin was still somewhat active after 100 hr. 

 irradiation. Similar effects of concentration or desiccation are often 

 met with among toxins and immune bodies. 



Loewenstein (107) reported inactivation of tetanus toxin by visible 

 light from a 0.25-amp. Nernst lamp, with and without interposition of 

 colored-glass screens of undetermined transmission. Loewenstein also 

 reported photodynamic inactivation by visible light acting on an unde- 

 scribed toxin-eosin mixture. It had been described previously by 

 Tappeiner and Jodlbauer (155) using 0.05 per cent eosin and diffuse 

 dayhght, and Huber (87) used eosin or erythrosin and found destruction 

 of the hemolytic effect in vitro as well as of the general toxicity. (Cf. 

 also above in reference to diphtheria toxin.) Oxygen is necessary. 



Flexner and Noguchi (61) noted photodynamic destruction of the 

 lytic and tetanospasmic principles of tetanus toxin both by sunlight alone 

 and, more rapidly, by sunlight acting on toxin solutions containing 

 0.15 per cent eosin or related dyes. Hausmann and Pribram (78) also 

 obtained photodynamic inactivation of tetanolysin, using ox or rabbit 

 gall as a sensitizer. 



Ultra-violet inactivation of tetanolysin, first described by Courmont 

 and Nogier (37), in 1909, illustrated well two points: the importance of 

 transparency to hght of the effective spectral region; and the characteris- 

 tic absence of the need for oxygen, which distinguishes most ultra-violet 

 reactions from the analogous photodynamic reactions. 



Influence of Dilution. — The first point is treated by Courmont and 

 Nogier (38) in a paper in which they show that while 1 to 2i^ hr. hardly 

 inactivated undiluted toxic tetanus bouillon in their earlier experiments, 



