322 CONTROL OF REPRODUCTION 



percentage of the cultures fruited, and that less time was required for 

 fruiting, at pH 3.0 or 4.0. 



The chemistry of the pigment is not known, although Seifriz and 

 Zetzmann (1935) have shown that it possesses the properties of an 

 indicator, and Allman (1955) has studied it intensively in connection 

 with the problem of estimation of the quantity of plasmodium by the 

 amount of pigment produced. We are presently concerned with certain 

 of the chemical and physical properties of the pigment, which appears 

 to be important in the photoinduction of fruiting. 



METHODS 



Complete removal of the yellow pigment present in the plasmodia 

 may be achieved by extraction with methanol, as recommended by 

 Allman ( 1955). As mentioned by Gray (1938), the yellow plasmodia 

 begin to lose their color shortly before fruiting begins. They eventually 

 become white or colorless. When the black sporangia of cultures which 

 had fruited one day previously were extracted with methanol, with 

 thorough grinding in a mortar, no trace of yellow pigment was appar- 

 ent. It seems clear that the yellow pigment characteristic of plasmodia 

 disappears completely upon fruiting. 



When examined with an ultraviolet light, the plasmodia of P. 

 polycephalum are strongly fluorescent. Methanol extracts containing 

 the pigment are hkewise fluorescent. A fluorescence spectrum was 

 taken, which showed two peaks at 473 m^i and 505 mix. It was there- 

 fore suspected that two pigments are present in the plasmodium. 



Accordingly, the methanol extract was chromatographed on strips of 

 Whatman No. 1 filter paper, by the ascending technique, with 3A^ 

 NH4OH as the developing solvent. Two yellow spots were found on 

 visual inspection. These spots were characterized by Rf values of 

 0.44-0.62 and 0.67-0.77. The two substances wiU be subsequently 

 referred to as component 1 and component 2, respectively. 



In order to separate quantities of the two pigments greater than 

 would be possible by paper chromatographic techniques, column 

 chromatography was employed. With a column of alumina measuring 

 approximately 1 X 10 cm, the methanol solution of the two pigments 

 could be separated. Component 1 is strongly adsorbed, and remains 



