For his outro solo in "Mother," guitarist John Christ uses hammer-ons and pull-offs to create furious lead passages and help bring the song to a powerful, climactic ending. Both hammer-ons and pull-offs use the left-hand's fingers alone to sound notes on the fretboard, and are indicated in the staff and tablature by curved lines called slurs. Only the first note at the beginning of each slur is picked. The second note is either hammered-on or pulled-off, depending on the direction of the line. (A higher note would be hammered-on while a lower note would be pulled-off.)
For the hammer-on technique (see Fig. 1), the left hand sounds the second note under the slur by striking the fretboard without the usual right-hand pick attack. As the technique's name suggests, you must hammer the finger down onto the fretboard with enough force in order for the note to achieve volume equal to the picked one. Simply placing the finger on the string will usually result in a weak, if even audible, note.
To perform the pull-off in Figure 2, begin by fretting both notes in advance using the fingerings provided beneath the tablature. Pick the E note, pull the string slightly towards the top two strings with your ring finger, then let go of the string, letting it snap back to sound the D note still fretted by the index finger). This pulling-and-releasing motion is what keeps the string vibrating and gives the second note its volume.
MAny of John Christ's most fiery licks in "Mother" involve using hammer-ons and pull-offs in combination. A great example of this can be found in measures 64 and 65. The best way to approach this monster riff is to work on smaller groups of notes. Start out slowly at first and don't try to play the licks up to speed until you've memorized most of the passage. You'll then be able to focus your concentration on the guitar, rather than the sheet music.
To comfortably perform the lightning-fast licks in "Mother" at tempo, you'll need to develop your left-hand finger strength and dexterity. I've provided a few hammer-on/pull-off exercises (see Figs. 3-6) which should help accelerate the process. Here are some guidlines for practicing them:

• Pick only the first note of each exercise, using the left hand to sound the remaining notes.
• Try raising your fingers at least two inches off the fretboard between hammer-ons and pull-offs. Stretching the fingers like this will help keep them limber.
• At some point you'll probably feel your left hand and forearm start to become warm of even stiffen up. If this happens, stop and relax! While this is part of the process of developing muscles and tendons, continually pushing yourself past this point may result in tendonitis! (Warning signs: sharp pains in the hand and forearm.)
• As you progress in your playing, try to create new exercises that challenge your level of ability.

  "lh" are the left-hand fingerings.
  
  
     Fig. 1      Fig. 2      Fig. 3       Fig. 4
                             Double       Double
     Hammer-on   Pull-off    Hammer-on    Pull-off
  e|-----------|-----------|---7h9h10---|---10p9p7----|
  b|-----------|-----------|------------|-------------|
  g|----7h9----|----9p7----|------------|-------------|
  d|-----------|-----------|------------|-------------|
  a|-----------|-----------|------------|-------------|
  e|-----------|-----------|------------|-------------|
  lh:   1 3         1 3        1 3  4        4 3 1
  
  
     Fig. 5                 Fig. 6
     Hammer-on/Pull-off     Hammer-on/Pull-off
     Exercise               Exercise
  e|-------7h9h10p9-------|-------10h14p10h12-------|
  b|----------------------|-------------------------|
  g|----------------------|-------------------------|
  d|----------------------|-------------------------|
  a|----------------------|-------------------------|
  e|----------------------|-------------------------|
  lh:      1 3  4 3                1  4  1  3
  
  

Danzig bassist Eerie Von puts the power pedal to the metal in this pumping parental rocker. Slamming out a chain of powerful eighth-note pedal tones beneath a series of chord changes (see measures 27-30), Eerie develops a degree of tension in the music that pulls in the listener, and then captures him. This type of device can spice up many a musical situation. While most rock songs commit the bassist to playing root-oriented bass-lines that outline the harmony in a straight-forward manner, playing pedal tones underneath a moving harmony creates enough tension to throw the listener off so that when you begin playing a more conventional line, the listener is ready to surrender. Try this device out on your own and you'll soon discover that it is not as easy as it may appear. Be selective when playing pedal points -- a little bit can go a long way. To get you started, try playing a pedal point on A while a guitarist friend plays the chord progression Am-F-G. Notice that the A pedal point sounds pleasing to the ear beneath each chord.
With all this tension being thrown around ("I FEEEEEL SOOOO TENSE!!!) it makes sense that Eerie would give us some release in the next section of the song. In section D, He lays roots on us, giving us a clear path down the harmonic highway. You may notice that the song hasn't lost any of it's momentum. This is due to the bands use of anticipation (hitting chord changes a half a beat early). Anticipation creates a string feeling of forward motion and allows the music to sail by, taking the listener along for the ride. Incorporating these devices into your own playing will give your bass-lines a more mature feel and style.
--Michael DuClos