Respitory proteids : researches in biological chemistry / A.B. Griffiths.

  • Arthur Bower Griffiths
Date:
1897
Catalogue details

Licence: Public Domain Mark

Credit: Respitory proteids : researches in biological chemistry / A.B. Griffiths. Source: Wellcome Collection.

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    Papilio (several species), Parthenos gambrisus, Hesperia, Limenitis procris. Nocture—Halias prasinana. Geometrre —Larentia (several species), Gidaria miata. Sphingidre— I)io statices. The same pigment is always yielded by each of these species. The wings are first treated with hot alcohol and ether, in which liquids the pigment is insoluble. The wings are then boiled in acidulated water and the filtrate is concenti’ated by evaporation—the green pigment being deposited as an amorphous substance. The mean of six analyses of this green pigment gave results answering to the formula CnHl2NsO10. The pigment is a dibasic acid, soluble in acids and pre- cipitable by silver nitrate. The mean of three analyses of the silver salt leads to the formula CnH]0Ag2N8On. The silver salt appears in silky, colourless needles very soluble in alcohol, but insoluble in ether. The alcoholic solution deflects the plane of polarisation to the right. Its specific rotatory power for the ray D is [a]D = +29°. By prolonged boiling with water the acid pigment yields urea, alloxane, and carbon dioxide : CnH12NsO]0 + 02 = 2CH4N20 + 2C4H2N204 + C02. By the prolonged action of boiling hydrochloric acid the pigment is converted into uric acid : CnH12N8O10 = 2C5H4N403 + C02 + 2H20. It is very probable that the green pigment is a deriva- tive of uric acid, and that it is deposited in the wings by the wandering cells, i.e., it is of an excretory character. The solutions of lepidopteric acid give no characteristic absorption bands when examined by means of the ordinary spectroscope or the microspectroscope. Lepidopteric acid is merely a decorative pigment.