AND BLOOD PRESSURE 1G9 



The greater part of the water passes rapidly out of the vascular 

 system, the glands all actively secrete, watery urine is passed, the 

 saliva drips, the guts become filled with watery solutions, the 

 lymph flows in a continuous stream from the abdominal organs 

 but not from the lymphatics of the limbs. After death the sub- 

 cutaneous and intermuscular cellular tissues and the central nervous 

 system and usually the thoracic organs are as dry as normal, while 

 the abdominal organs are markedly cedematous and the peritoneal 

 cavity contains fluid. Scalding, toxic agents, temporary anaemia, 

 by altering the vascular tone and conditions of surface and osmotic 

 energy l of a limb, render it cedematous when the state of hydraemia 

 is produced. An hydraemia maintained by daily injection has the 

 same effect, so that ligation of the femoral vein, which normally 

 does not produce oedema in the animal, in such case does. 



A number of toxic substances are known which have the effect 

 of so altering the relations of osmotic and surface energy that 

 hydraemia causes oedema in the limbs. The oedema which occurs 

 in renal disease is probably to be explained on these lines. The 

 factors to consider are a scanty output of urine, particularly of 

 solid constituents, retention of salts and other waste products, 

 with consequent alteration in osmotic conditions leading to the 

 passage of fluid into the tissue spaces ; excessive metabolism of 

 the muscles resulting from the defect of renal functions ; an effort 

 on the part of the tissues to excrete into the body spaces waste 

 substances (this is the normal process in the ascidian) when the 

 nephridial tissue fails. Mellanby maintains that the creatin 

 found in the muscles is a waste product stored therein with 

 advancing life. 



The injection into the blood of a concentrated solution of a 

 crystalloid such as sugar produces hydraemia. Water is drawn 

 from the tissue space into the blood vessels and to such an extent 

 that the injection of 45 c.c. of 75 per cent, solution of dextrose may 

 temporarily double or treble the volume of blood fluid in a dog, 

 as measured by the alteration in number of red cells (Starling). 

 The lymph flow which is greatly increased in quantity is ascribed 

 to increased capillary pressure and filtration. In confirmation of 

 this view Starling found that if he drew off an adequate amount of 



1 If a shrunken tissue cell border on a distended capillary, the surface tension of 

 the capillary will be high and its energy low ; while the surface tension of the tissue 

 <' 11 will be low and its energy high the one strives to shrink, the other to swell. 



