126 



318 J. A. MACWILLIAM 



(Chaffard and his school) and Russian investigators. Cantieri's (25) 

 results oppose this idea; he found no relation, in acute or chronic 

 nephritis, between the blood pressure and the cholesterin content of 

 the blood, which in a series of arterio-sclerotic cases was rather below 

 the normal content; also administration of cholesterin does not raise 

 the blood pressure. 



Dixon and Halliburton (37) ascertained that the pressor effect of 

 cholesterin given by intravascular injection is negligible. 



As regards urea, though high blood percentages of this substance 

 and high blood pressure are often found together, the relation is very 

 variable and it is evident that it is not a causal one. The same state- 

 ment holds good with regard to the viscosity of the blood, though a 

 group of high pressure cases associated with polycythemia has been 

 recognised. 



The search for pressor bodies of endocrine origin (though possibly 

 present in toxemia in pregnancy, etc.) as a cause of persistent high 

 blood pressure has so far proved futile, and the same is to be said with 

 regard to the conceivable possibility of a lack of depressor substances 

 as an operative influence. A similar remark applies to the question of 

 retained pressor bodies when a rise of pressure follows reduction of the 

 kidney tissue below a certain limit, e.g., to one-third, as studied by 

 Passler and Heincke (106), Janeway (70) (with Carrel) and others. 

 It is a remarkable fact that no adequate explanation is available as to 

 how suppression of kidney function kills. 



In the presence of structural kidney damage the question of altered 

 function becomes added to that of diminution of functional area. 

 Extracts of kidney have been found by various observers to have 

 pressor effects — Tigerstedt and Bergman's (125) "renin" — and the 

 throwing off of some such pressor agent from disintegrating renal 

 tissue in diseased conditions has been suggested (for some cases of 

 hypertension) by Eatty Shaw (12) ; it has not been found practicable 

 to establish the presence of such agents in the circulation. On the 

 other hand there is the possibility that the whole condition (hyper- 

 piesia) in which persistent high blood pressure is present may be due 

 to toxic agents in the general circulation, secondarily affecting the 

 kidneys and thus leading to an aggravation of the morbid effects. 



The latest pressor substance suggested is guanidine, studied by 

 Major and Stephenson (92). These observers observed powerful 

 effects, doubling or tripling of arterial pressure in a few minutes, from 

 intravenous or intramuscular injection of guanidine salts in dogs, — 



