code: public void release(Particle particle) {
  		if (particle != dummy)
  		{
  			ParticlePool pool = (ParticlePool)particlesByEmitter.get( particle.getEmitter() );
  			pool.available.add(particle);
  		}
  	}
docs: Release a particle back to the system once it has expired
  
  @param particle The particle to be released