404 ANNUAL BEPORT SMITHSONIAN INSTITUTION, 19 32 



During menstruation the blood bactericidal power was lowered 

 and irradiation appeared to make this even worse.^^ In experiments 

 in which rabbits were given a septicemia, the bactericidal power 

 of the blood fell to a very low degree and was not improved by 

 irradiation, thus supporting the view generally held that in the 

 treatment of acute infections by light one should be very cautious. 

 Very aged patients have been considered to have their resistance 

 to infection lowered by the injudicious application of light.^^ In 

 tuberculosis overdosage has produced focal reactions that have done 

 harm ; light may set up a focal reaction similar to that of tuberculin. 

 In anemic rats careful irradiation has led to a rapid regeneration 

 of erythrocytes and hemoglobin; but if the irradiation was too 

 vigorous, blood cells were destroyed.^^ Overexposure to ultra-violet 

 has rendered ergosterol inactive against rickets. On the other hand, 

 prolonged and intense irradiation of rats with ultra-violet (over a 

 period of six months) had no unfavorable effect on the rate of 

 growth or on the size or appearance of the endocrine glands. 



In some cutaneous disorders (eczema, psoriasis, lupus erythemato- 

 sus, herpes simplex, erythema solare perstans, xeroderma pigmento- 

 sum, freckles, atrophy, keratoses, prematurely senile skin) exposure 

 to such rays maj'^ cause an exacerbation, provoke an attack, or 

 produce other injurious effects. 



The schedule for increasing the period of exposures with various 

 sources of light must vary. The physician is to be guided chiefly 

 by the signs and symptoms evinced by the patients in their response 

 to treatment, in addition to the skin reactions. Furthermore, in 

 disease such as tuberculosis, the selection of a form of light therapy 

 may depend on the state of activity or on the type of disease to be 

 treated ; thus, with a febrile advanced case, one would usually prefer 

 to avoid using heat rays. One may also have to depend on the 

 source of light available or be influenced by the season of the year. 

 Furthermore, a failure in response to one form of light therapy 

 may be an indication for the trial of another form, or possibly many 

 forms of light therapy may have to be combined in various ways. 

 I have found that some patients with sallow complexion showed little 

 skin erythema on the first exposure to the mercury-vapor quartz 

 lamp, but if previously treated with from three to four doses of the 

 carbon arc lamp they later reacted with erythema. There may exist 

 contraindications to light therapy which are not yet clearly under- 

 stood but which later with more experience may become evident. 



" See footnote 38. 



"2 Gauvain, H., Lecture to the National Tuberculosis Association, Washington, D. C, 

 1927. 

 6«Kestner, O., Zeltschr. f. Biol., vol. 73, p. 1, 1921. 



