ORGANIC BISMUTH COMPOUNDS. I 507 conditions. The reversal of the relative speeds of hydrolysis of lactose and maltose that was predicted by E. F. Armstrong and Caldwell has been realized. Washington, D. C.
THE biological importance of short waves of light is commonly recognised, but careful investigations have not shown any significant action of visible light on the biological functions of the animal.It was found, however, that many fluorescent dyes sensitise biological reactions to the action of visible light. The fluorescence of these substances consists of much shorter waves than the waves of light which they are absorbing. Hausmann (1,2,3,4,5) showed that h8ematoporphyrin, which is a fluorescent substance, can sensitise not only protozoa and blood cells but also whole organisms of higher animals to the action of light. Mice injected with haematoporphyrin become very sensitive to light. The exposure of such animals to the action of the sun causes acute skin inflammation followed by death. Only meso-and homo-porphyrins show any heematoporphyrin-like action; other derivatives of hs3moglobin or chlorophyll are without light-sensitising properties(6). HaTmatoporphyrin alone is not changed chemically when exposed to the action of light (7).Fischer(s) found that the urine and fwces of light-sensitive men such as those suffering from certain skin diseases (variola vacciniforme) contain hematoporphyrin-like bodies. Meyer-Betz (7) showed that man can be sensitised to the action of light by injections of hwmatoporphyrin. The symptoms of this artificial light-hypersensitivity were similar to those described in human disease.Haematoporphyrin seems to be a general sensitiser of photo-chemical reaction. Photographic plates can be sensitised to the action of yellow light by means of hwmatoporphyrin solution. Sunlight causes a destruction of fibrinogen in the presence of h&matoporphyrin solution. The systemic action of visible light on the organs of haematoporphyrinsensitised animals has not been studied previously. The consideration of this problem forms the substance of the present paper.
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