Thi s book is a general introduction into in vivo chlorophyll fluorescence and contains the contributions of the first International Ch 1 orophyll Fluorescence Sympos i urn he 1 din the Phys i kzentrum Bad Honnef, F. R. G. from June 6 to 8, 1988. This Symposium was made possible by a generous support from the Wilhelm and Else Heraeus Foundation, Hanau, which is gratefully acknmvledged. The book not only comprises all aspects of the applications of chlorophyll fluorescence in photosynthesis, stress physiol- ogy, hydrobiology and remote sensing, but also gives access to measuring techni ques, data acqui si ti on and earl i er 1 iterature references. Thus it is far more than just a common proceedings book, it is a general introduction to all forms of application of the non-destructive in vivo chlorophyll fluorescence including the newest results. In a first chapter the inverse correlation between in vivo chlorophyll fl uorescence and photosynthet i c quantum convers i on and CO?-ass i mi 1 at ion is outlined, the origin and life-time of the chlorophyll fluOrescence at room and liquid nitrogen temperatures are given as well as the induction kinetics (Kautsky effect) and the methodo 1 ogi ca 1 approaches to regi ster different forms of chlorophyll-fluorescence signatures.