The following text forms the proceedings of a conference. It is supposed to contain what was actually reported and discussed, though it does this, one hopes, in a polished and organized way. A sense of actuality, a reporting quality, makes this book different from a collection of review papers as, for example, a book in the series on Stars and Stellar Systems. All Invited Reports have been included as the Reporters wrote them. The Editor's task has been restricted to improving the presentation, a process which in most cases involved only minor revisions. In a few Reports the Editor did some heavy rewriting; in those cases he checked with the Reporters. Obviously a different course had to be taken with respect to the Discussions. They were recorded on tape, transcribed verbatim and then passed back to the discussants. After the discussants returned their versions, the Editor rearranged and condensed the texts and made a considerable effort to provide references. (Unfortunately he was not able to locate all relevant Russian papers from 1968 and 1969. ) The Editor takes the responsibility for mistakes made in this process, which may have produced occasionally his own 'mix-master Universe'. Actually only a few discussion remarks were rejected, more often because of incomprehensibility, rather than because the remark was far from the subject of the Symposium, or was too long, or was too trivial. A few very long remarks have been condensed and put at the end of a Discussion.

Proceedings of the 6th Symposium on Cosmic Gas Dynamics organised jointly by the International Astronomical Union and the International Union of Theoretical and Applied Mechanics, Yalta, The Crimea, U.S.S.R., September 8-18, 1969

Inhalt
I Description and General Theory of the Interstellar Medium.- 1. Review of Cosmical Gas Dynamics.- 2. Discussion following van de Hulst's Report.- 3. Some Characteristics of Interstellar Gas in the Galaxy.- 4. Theoretical Description of the Interstellar Medium.- 5. Discussion following the Reports by Weaver and Field.- 6. Discussion following the Informal Meeting on Interstellar HI Clouds.- 7. Collective Plasma Phenomena and their Role in the Dynamics of the Interstellar Medium.- 8. Discussion following the Report by Kadomtsev and Tsytovich.- 9. Observational Aspects of Galactic Magnetic Fields.- 10. The Origin and Dynamical Effects of the Magnetic Fields and Cosmic Rays in the Disk of the Galaxy.- 11. Discussion following the Reports by Parker and Verschuur.- 12. The Gas Dynamics of Accretion.- 13. Discussion following Spiegel's Report.- II Interaction of Stars and Interstellar Medium.- 14. Mass Balance of Interstellar Gas and Stars.- 15. Supernovae and the Interstellar Medium.- 16. Discussion following the Reports by Salpeter and Woltjer.- 17. The Solar Wind an Example of a Cosmical Plasma and a Stellar Wind.- 18. Discussion following Lust's Report.- 19. Mass Loss from Stars.- 20. Mass Loss from Eruptive Stars.- 21. Discussion following the Reports by Pottasch and Boyarchuk.- 22. Interstellar Grains and Spiral Structure.- 23. Interstellar Molecules (with an Appendix on H2 by E. E. Salpeter).- 24. Discussion following the Reports by Greenberg and Stecher.- 25. Protostars and Other Neutral Condensations in HII Regions.- 26. Discussion following Mezger's Report.- 27. Final Discussion.- Index of Discussion Remarks.