117 



BLOOD PRESSURES IN MAN, NORMAL AND PATHOLOGICAL 309 



insurance. Women at all ages were 8 mm. below the male average, 

 with the same ratio of increase at similar ages. 



In Symonds' (122) report of 150,419 men successive age groups are 

 presented from a 15 to 19 year group up to one of 60 years and over; 

 also build groups (Medico-Actuarial Investigation I, 1912, 120) based 

 on the average weight for each inch of height in men at the age of 37. 

 Systolic pressure alone is studied. Age, weight and pressure are shown 

 to increase together. Differences appear of 11 to 12 mm. between the 

 youngest and the oldest in each build group, and of 10 mm. between 

 the very light and the very heavy groups; even at the ages of 60 and over 

 the difference was much the same. In the whole series the pressure 

 averages range from 121.2 mm. in the youngest (15 to 19) group to 

 135.2 mm. in the oldest (60 and over) group. Mackenzie (87) reporting 

 on 18,637 men, gives a range from 119 mm. to 137 mm. in similar age 

 groups. Rogers and Hunter's (113) 62,000 rise from 120 mm. at 15 

 to 19 to 134 mm. at 55 to 59; the results of Fisher (46) and Goepp (56) 

 are very similar though the age grouping differs slightly. As regards 

 the pressures in women, Symonds' 12,000 with age grouping similar 

 to the men show values ranging from 119.2 to 135.5 — a much closer 

 approximation to male pressures than has been found by most observers 

 who have commonly reported pressures in women, at least in the 

 first half of life, as 8 to 10 mm. lower than in men. 



In a recent valuable study Stocks and Karn (120) present continuous 

 evidence of the pressure behaviour through the ages of puberty and 

 adolescence, from the ages of 5 to 40 years. They submit curves and 

 tables for the correction of pressure readings for age, weight (affecting 

 systolic pressure) height (affecting diastolic pressure) and pulse rate. 

 They find that there is a positive correlation of systolic pressure with 

 muscular strength apart from physical development and age. By 

 their method of correlation with pulse rate they believe that an ap- 

 proximate correction of the well-known disturbing effects of psycho- 

 logical factors, such as nervousness, can be made. With regard to 

 this conclusion of Stocks and Karn it is to be remarked that excitement, 

 emotion, etc., influence blood pressure by acting on the vasomotor 

 centre as well as on the heart, and that the relation between the two 

 actions is by no means constant; hence the pulse rate cannot be relied 

 on to give accurate indications of the degree of pressure alteration 

 developed, though a correction for pulse rate no doubt diminishes the 

 amount of the error. The range of apparent variability of the blood 

 pressure in healthy persons is substantially diminished by such cor- 



