The general discussions of the roles of photometric and spectroscopic classification at Cordoba in 1971 (lAU Symposium No. 50), and of the calibration of classification indices at Geneva in 1972 (IAU Symposium No. 54), revealed clearly the steadily in creasing importance of abundance parameters. The multipliCity of these, however, raised so many new problems that it was logical that the 1975 meeting at Lausanne should be concerned with ways in which differences in abundance affect both spectral types and photometric indices. Commissions 29 and 36 joined with Commission 45 in sponsoring this Symposium. Since the date of the meeting came shortly after the formal retirement of Professor William W. Morgan from the University of Chicago, it was quickly agreed that this meeting should be dedicated to him in recognition of his unique contributions to spectral classification. In the opening paper of the Symposium Dr. Bengt Stromgren has summarized these. To his remarks we should add only that it was about 1940 that Morgan first distinguished the group of G- and K-type stars with weak CN bands and metallic lines - stars which have since been recognized as having the abundance of all metals relative to hydrogen much lower than in stars of the solar population. Spectra of two of these, HD 81192 (Boss 2527) and 8 Lep, were later shown as examples of the group in the Yerkes Atlas of 1943.

Inhalt
I / Influence of Abundances Upon Stellar Atmosphere Calculations.- (Invited Lecture).- Synthesis of Classification Dispersion Spectra from Stellar Atmospheres Theory and from High Dispersion Spectra.- A Model-Atmosphere Analysis of the Spectrum of Arcturus.- Influence of Uncertainties of Molecular Data upon the Determination of Abundances in Cool Stars.- On the Spectral Classification of Cool White Dwarfs.- Effects of Abundance Changes on the Spectra of Very Cool White Dwarfs.- II / Some Comments on a Catalogue of Atmospheric Parameters and [Fe/H] Determinations.- (Invited Lecture).- III / Derivation of Abundances through Photometric and Spectroscopic Methods.- (Invited Lecture).- Abundance Effects for the A0-G2 Stars in the Geneva System.- Abundance Effects on uvby Photometry.- A Test of the Accuracy of Low Dispersion Objective Prism: Spectral Classification of Late-Type Stars Using DDO Photometry.- Observed Relations between Physical Properties and MK Classification as Functions of Metal Abundance for F5-K4 Stars.- Narrow-Band Photometry of A and F Stars.- The Helium-to-Hydrogen Ratio of Stars in Young Clusters and Associations.- Recent Results Pertaining to the Helium-Rich Stars.- Abundance Effects in the Classification of K Stars.- Comparison of Colour Curves of Mira Stars of Spectrum M and S.- The Colour Excess Scale and Intrinsic Colour Properties of the Longer Period Cepheids.- On the Derivation of Abundances by means of Features in the Sequences of the Old Open Star Clusters.- A Method for Determining the Chemical Composition Parameter (X, Y, Z) of Galactic Clusters.- IV / Abundance Effects in Spectral Classification.- (Invited Lecture).- HD Stars South of ? = ?53° Having Peculiar Abundances: Statistics and Notation.- The Bonner Spectral Atlas andThree-Dimensional Classification at Low Dispersions.- The Spectral Type of HD 101065.- Classification of Stars with Different Chemical Constitution.- Effects of Heavy-Element Abundance on Classification of G-Type Giants.- Spectral Classification in the Small Magellanic Cloud.- Nitrogen and Carbon Anomalies in OB Spectra.- Infrared Lines in Peculiar Emission-Line Stars.- Conflicting Evidence on the Composition of Am Stars.- Ultraviolet Spectrophotometry of Early-Type Stars.- Mass Estimation of Twelve K Dwarfs.- Can we Check by High-Dispersion Analyses Stars Belonging to Eggen's Moving Groups?.- Spectral Classification of B and A Stars from Data of S2/S68 Experiment.- V / Abundances in Stellar Populations.- (Invited Lecture).- A Population Discriminant in M-Dwarf Spectra.- Chemical Evolution of the Galactic Disk and the Radial Metallicity Gradient.- Abundances in the Galactic Clusters of Hyades and M 67.- Curve-of-Growth Analysis of a Red Giant in M 67.- Some Comments on the Age-Abundance Relation.- Remarks on Some Aspects of Spectral Classification.- Appendix / A Catalogue of [Fe/H] Determinations.- A Catalogue of [Fe/H] Determinations.- Index of Names.