1. Introduction
2. Observations and Data Reduction
3. The Spectra
4. Analysis
4.1. Excitation Temperatures and Column Densities
4.2. Abundances Calculations
5. Results and Discussion
5.1. Chemistry
5.2. Isotopic Ratios
5.3. Hydrogen and Helium Recombination Lines
5.4. Line Profiles
5.5. Comparison with the Spectra of IRC+10216 and CRL 618
6. Summary