352 BIOLOGICAL EFFECTS OF RADIATION 



Protein-free toxic filtrates produced by bacteria of the colon-typhoid 

 group studied by Welch (162) produce two types of phenomena in vivo: 

 a "skin reaction," and a "skin reactivity," i.e., sensitization to subsequent 

 injections. The latter might be classed as an antigenic property. It is 

 abolished by 60 to 70 min. irradiation at 25 cm. from a 55-volt, 30-amp,, 

 direct-current carbon arc, while the skin-reaction test (toxin?) is abolished 

 after 40 min. 



Toxins Present in Human Serum. — Macht (112) has detected by their 

 effects on the growth of seedlings of Lupinus albus several toxic sub- 

 stances, among which two have been tested as to their stability on ultra- 

 violet irradiation. Pernicious-anemia toxin, present in serum in that 

 disease, was found to be about 20 per cent inactivated by 30 min. irradia- 

 tion. Eosin accelerated destruction: presumably a photodynamic effect 

 accompanying visible light. Menotoxin, which Macht believes to be 

 related to cholesterol, is apparently unaffected. 



ANTIGENS 



Many of the toxic materials discussed above have the power to evoke 

 changes in mammals upon injection or introduction per os. Many 

 materials, such as the antigens used in the Wassermann reaction, evince 

 very little toxicity. For convenience, therefore, we shall group together 

 here the antigenic aspects of all these substances, even though their 

 toxicity may have been considered above. 



Tuberculin. — The various tuberculins produce no toxic symptoms in 

 normal animals, and cannot, therefore, be considered as toxins. Neither 

 do they appear to be, strictly speaking, antigens. Their inclusion here 

 is arbitrary. The different types all seem to be more or less sensitive to 

 irradiation. 



Jansen (93) exposed previously heat-killed and dried B. tuberculosis 

 in layers 0.3 to 0.5 mm. thick to concentrated carbon-arc light without 

 effect; three types of tuberculin irradiated under similar conditions gave 

 the characteristic odor of burned horn, but had exactly the same effects 

 on tuberculous guinea pigs as the controls. Visible light is, therefore, 

 by itself practically without effect. 



However, the addition of eosin or erythrosin may lead to inactivation. 

 Bouveyron (21) added 2 per cent dye to 1 per cent Institut Pasteur 

 tuberculin (saturated with chloroform) and exposed it for several hours 

 to clear July sunlight. Controls without dye and/or wrapped in black 

 paper produced the typical cutaneous reactions in tuberculous guinea 

 pigs, while the sample irradiated with dye did not. The same result was 

 attained by 12 hr. exposure to a 1000-cp. electric light at 20 cm. distance. 



The earlier findings of Jacobsohn (90) are in apparent conflict with 

 this, but his exposure of the tuberculin to diffuse daylight for 24 hr. is 

 not nearly equivalent to Bouveyron's exposure of about 12 hr. to direct 



