Abstract
While at Woods Hole one of us (Alvarez) became interested in the green color of the intestine of the otherwise white Chaetopterus. On turning to the article by Enders 1 it was found that doubt still exists as to the nature of the pigment: some have thought it to be biliverdin, others have assumed it to be chlorophyll, and others have been so sure that it is not chlorophyll that they have dignified it with a special name, chaetopterin. It seemed worth while to settle the question because if the pigment should be biliverdin, the animal might be valuable for studies on bile formation.
The digestive tracts from several worms were accordingly extracted with alcohol and determination made by one of us (Sheard) of the percentage transmission of light of various wave lengths (from 700 mμ to 430 mμ) with a Keuffel and Esser color analyzer (spectrophotometer). The transmission curves (Fig. 1) obtained from the unknown pigment and from solutions of chlorophyll from the fresh stems of buckwheat, leaves of bean plants and grass were so similar as to warrant the statement that the absorption bands (zones) were produced in all cases by the same pigment or pigments, that is, by chlorophyll a or chlorophyll b or both. The most pronounced absorption zone in an alcoholic solution of chlorophyll has its maximal point at about 660 mμ. This band is common to all the curves of Fig. 1 irrespective of the source of the coloring material or degree of dilution of the solution. Curve 2 was obtained from an alcoholic extract of the stems of buckwheat, the solution being of such a concentration as to reproduce as nearly as possible Curve 1 (alcoholic extract of chaetopterus), both in respect to the number of absorption zones and their degree of absorption.
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