In a study of the effect of postural alterations on the cerebrospinal fluid pressure, two objections in particular may be made to the attempt to apply observations on animals to human beings: first, the common use in animal experimentation, for example, of ether, an anesthetic which has been definitely demonstrated to disturb the dynamic conditions within the intracranial cavity; second, the difference between the postural habits of man and those of four-footed mammals, which may result in dissimilar pressure reactions when the position of the body is altered as a result of the variations in their respective vascular compensatory mechanisms.
With these objections in mind we have performed on man certain postural experiments, some of which have heretofore been made, and have added some measurements of cerebrospinal fluid pressure in positions which have not been previously utilized, at least in the human subject. The experiments were divided to learn the