We show that if a hyperbolic knot manifold M contains an essential twice-punctured torus F with boundary slope ? and admits a filling with slope ? producing a Seifert fibred space, then the distance between the slopes ? and ? is less than or equal to 5 unless M is the exterior of the figure eight knot.

Chapters1. Introduction2. Examples3. Proof of Theorems and4. Initial assumptions and reductions5. Culler-Shalen theory6. Bending characters of triangle group amalgams7. The proof of Theorem when $F$ is a semi-fibre8. The proof of Theorem when $F$ is a fibre9. Further assumptions, reductions, and background material10. The proof of Theorem when $F$ is non-separating but not a fibre11. Algebraic and embedded $n$-gons in $X^\epsilon $12. The proof of Theorem when $F$ separates but is not a semi-fibre and $t_1^+ + t_1^- >0$13. Background for the proof of Theorem when $F$ separates and $t_1^+ = t_1^-=0$14. Recognizing the figure eight knot exterior15. Completion of the proof of Theorem when $\Delta (\alpha , \beta ) \geq 7$16. Completion of the proof of Theorem when $X^-$ is not a twisted $I$-bundle17. Completion of the proof of Theorem when ${\Delta }(\alpha ,\beta )=6$ and $d = 1$18. The case that $F$ separates but not a semi-fibre, $t_1^+ = t_1^- = 0$, $d \ne 1$, and $M(\alpha )$ is very small19. The case that $F$ separates but is not a semi-fibre, $t_1^+ = t_1^- = 0$, $d>1$, and $M(\alpha )$ is not very small20. Proof of Theorem