reasons (as we may see in drunkenness and raving) and hindereth or preventeth the motion.
The spirits ought also to be more subtill; because they are to passe like a thunder through the bodies of the nerves. So, as the vitall spirits are carried to the parts of the bodies by the arteries, so the animall are carried by the nerves.
The animall spirits for this cause also ought to be subtill because the reasonable soul is resident in the brain, which doth contemplate things immateriall, as Angels and it selfe."
Although this may be taken as illustrating the teaching of the day, and the work of Willis, De Cerebri Anatome (1659) was no advance thereon, there appeared ten years later (1669) a treatise on the anatomy of the brain by Nicolas Stensen, whose investigations on secretions have already been referred to, which foreshadowed in several respects many of the discoveries made and views held a century and more later. But the special feature of this treatise as bearing on my present subject is that after pointing out the extremely slight information possessed as to the essential structures of the nervous system Stensen refused to admit in face of the lack of all sound anato-
