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BLOOD PRESSURES IN MAN, NORMAL AND PATHOLOGICAL 319 



effects opposed by CaCU, KCl or NH4CI given intravenously. In 

 experimental uranium nephritis (dogs) a marked and persistent diminu- 

 tion in the excretion of guanidine bases was found. In a number of 

 patients with high blood pressures — essential hypertension or with 

 chronic nephritis — a decreased output of guanidine was observed, as 

 compared with the normal daily average of 100 mgm. in normal per- 

 sons and in patients with normal blood pressure and temperature. It 

 is suggested that kidneys only slightly damaged, e.g., with small vessel 

 sclerosis, might have difficulty in excreting guanidine while other sub- 

 stances might pass and the renal defect fail to be rendered evident by 

 the usual tests till the change has progressed further. With regard to 

 this question evidence is desirable as to the blood pressure in the con- 

 dition of tetany (e.g., from parathyroid defect) where guanidine has 

 been detected in the blood by Noel Paton (107) and his fellow workers. 

 It would also be of interest to find whether any types of high blood 

 pressure cases are favourably influenced by administration of para- 

 thyroid and calcium salts. 



The normal relation of blood pressure to the body weight in the 

 healthy state has been shown to be a definite one, as illustrated by the 

 insurance statistics of Symonds and others and by the series of obser- 

 vations of Faber and others, increments of about 10 mm,, etc., being 

 found by Symonds in individuals of heavier build at all ages, while 

 the young subjects of Faber showed differences of 6 mm. according 

 to their build. While this appreciable difference holds good in healthy 

 persons the effects of obesity are much more pronounced and have 

 been emphasised by various observers. Among recent investigations, 

 Aubertin's (2) 70 obese subjects (average age 60) showed high pres- 

 sures in the great majority, only 7 being at or under 150 mm. while 

 24 non-obese controls of similar age averaged 149 mm. While greater 

 degrees of obesity were associated with higher pressures, arterial 

 sclerosis and chronic nephritis were not found to be the effective con- 

 nection between obesity and high pressure. Apoplexy and sudden 

 death are evidently related to the high pressures rather than the as- 

 sociations or effects of obesity acting in other ways. It is note- 

 worthy however that Symonds states that fat elderly subjects in good 

 condition and acceptable for insurance commonly have systolic pres- 

 sures below 140 mm. on an average. 



Relation of high pressures to the regulating mechanisms. Marey's 

 Law. Under the circulatory conditions of normal life this law is one 

 that is more honoured in the breach than in the observance. An in- 



