The ordinary systolic pressure-range is about 10 millimeters Hg, increasing to 40 or 50 or more in "mental° activity of a somewhat greater intensity. The usual diastolic range is about 8 millimeters Hg, save in old persons, and it has a lower maximum. Vasotension is a ready in dex of the intellectual and affective psycho physical dynamism ("power of concentration))) of an individual, and as such has value as a mental test; it is also a useful index of "nervousness° and of mental derangement perhaps.
Aments (except microcephs?) sometimes have a spontaneous systolic range of no more than 2 or 3 millimeters Hg for many minutes at a time, and a mental activity-range of 5 or 10 millimeters. Complete dements exhibit some thing of the same arterio-stasis but with a ten dency to large progressive excitement-rises not observed in aments. One microceph had a large and quick diastolic range and a normal systolic curve. Imbeciles and morons show varying degrees of the systolic plateau more or less according to mental status and dynamism; but there are many exceptions.
No personal, racial, sexual or age-differences in the variability have appeared; each hemo barogram is unique and always an interesting and accurate "human document." Sudden mental activity, apparently of any sort (e.g., multiplication, imagination of any kind of personal activity, transfers of the at tention-line, attention to the arm-sensations, dynamic associations, unpleasant or pleasant ef fects) ; active inhibition; breath-holding, and gradual subconscious increase of psychophysical tonus, increase both the systolic and the diasto lic tensions, especially the former; so does phys ical exertion proper.
Really passive relaxation of the muscles and of the mind; quiet, prolonged recall of happi ness; sleep-suggestion ; humor; deep breathing, and usually sensations of pleasure not allowed to excite, cause a lowering of both pressures. Marked rises in both tensional phases occur without conscious accompaniment, suggestive if not demonstrative of the subconscious actions of mind. Reciprocal variation of the systolic and the diastolic is very frequent, yet in some cases the two parallel each other for many minutes at a time. True emotion (adrenin and blood-sugar are suggested) lasts much longer than pretended emotion and "causes° ( ?) more variation.
Imaginary neuromuscular fatigue exerts a strong vasomotor influence. Lapsus attentionis lowers both tensions suddenly and far.
These are some of the chief personal con siderations. The medical relations are too com plex to he reported; less has been accomplished in this field of application.
Very numerous topics have been developed by physiologists since the preceding revision of this Encyclopedia was made, but these seem to the present writer to be fair examples of the most important directions. The World War will deflect the research-activities of the science into more practical (if not more useful) lines, at least for a time. The average phys iologist will then have a broader mind and will realize, often for the first time, that his great and fundamental science, as the one dealing with organic functions, is more than a study of "nerve-muscle-preparations,° that it may be made one of the two foundation sciences of personal human life.