Watch the Chromatic Two Five online guitar lesson by TrueFire from Play Jazz Guitar 9: Advanced Lick Vocabulary
Chromatic Two Five - Lick 49 is a video guitar lesson presented by Tom Wolfe and is sourced from 50 Hard Bop Blues Licks You MUST Know.
The last 4 bars of a blues can be harmonized very simply with a harmonic movement of the IV chord to the V chord and then to the root. But, when approaching the bebop blues progressions, the harmonic practice is to play a ii-V (minor 7th to dominant 7th chord) and then a turnaround - I-vi-ii-V back to the top of the form. This lick is a very chromatic approach to playing over this progression and more defined by the use of non-harmonic tones to emphasize the harmonic tones (the tones that fit in the chords).