^ CONTENTS 



Photophosphorylation and Photohydrolysis in Cell-Free 



Preparations of Blue-Green Alga 621 



Barbara Petrack and Fritz Lipmayrn 

 Photochemical Reduction of Triphosphopyridine 



Nucleotide by Illuminated Chloroplasts 631 



Anthony San Pietro 



V. BIOLOGICAL RESPONSES TO LIGHT 



Introductory Comments 645 



K. Hartline 

 Phototropism 646 



Kenneth V. Thimann and George M. Curry 



Discussion 6/0 



Photoperiodism, Chelating Agents, and Flowering of Lemna 



perpusilla and L. gihba in Aseptic Culture .... 673 



Williayn S. Hillman 

 Comparative Studies on the Growth and Light Sensitivity of 



Green and Etiolated Pea Stem Sections 687 



A. W. Galston and Ravindar Kaur 

 The Intensity Factor in Vision 706 



W.A.H.Rushton 



Discussion 721 



The Molecular Organization of Visual Systems 724 



George Wald 



Discussion 749 



Speculations on the Interrelations and Evolution of Photic 



Organs 754 



John Buck 

 The Color Vision of Insects 771 



Timothy H. Goldsmith 

 Electrophysiological Evidence for a Mechanism of Color 



Vision in the Goldfish 795 



E. F. MacNichol, Jr., M. L. Wolharsht, and 



H. G. Wagner 

 Discussion °1^ 



VI. SUMMARY 817 



Bent ley Glass 



Author Index of Participants 913 



Index 915 



