Abstract
It is the greatest possible pleasure and honour to write this chapter in honour of the sixtieth birthday of Professor P. A. Gammelgaard, whose delightful personality has contributed so much to the international surgical scene. Apart from his surgical skill, Professor Gammelgaard has done so much to advance the true science of surgery, particularly in this field of reno-vascular hypertension, where from the earliest days when in some centres enthusiasm tended to outrun discretion, he has aimed at providing sober quantities criteria from which to evaluate the methods of investigation and results of this new branch of surgery.