TOTAL CELL SURFACE AREA AND LIGHT ATTENUATION 



From the highest count and an assumed mean cell 

 diameter of 30 microns, the total cross-sectional area of 

 Gymnodinium flavum in the volume of water represented Ipy the 

 cylindrical light path, 1. 9 cm in diameter by 50 cm in length, 

 was computed. This figure, 3.87 cm^, exceeded the cross- 

 sectional area of the light path, 2.83 cm^, by more than 36 

 percent. It supplied a rough estimate of light-intercepting 

 capacity, but assumed a nonrandom distribution and neglected 

 scatter and selective absorption. 



THEORETICAL MODEL FOR DETERMINING POPULATION 

 DENSITIES OF UNICELLULAR FORMS 



A theoretical model for determining the population 

 density of single-celled forms using size data for Gymnodinium flavum 

 and based on light absorption was constructed. Four 

 assumptions were made to construct the model and to derive 

 curves which were compared to scatter diagrams of 

 Gymnodinium flavum and total microconstituents in both opera- 

 tions. While each of them was recognized as being a rough 

 approximation, the calculation was of interest as a possible 

 indication of relationships between unicellular forms and 

 light attenuation. Furthermore, as the number of organisms 

 /V increases, the situation should more nearly approximate 

 the assumptions. 



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