84 ABNORMAL INCREASE IN THE AMOUNT OF BLOOD. 



The weight of the blood of mice has been found to be from y^ to -^ 

 of the body-weight, exclusive of gastric and intestinal contents; of 

 guinea-pigs - 1 (from -^ to - 1 ) ; of rabbits ^ (from ~ to -^-) ; of dogs 

 1 3 (from 4 to ^); of cats ~; of birds from ^ to ^- of frogs ^ to ~; 

 of fish from ^ to ^. 



Vierordt's method, which is based upon the determination of the amount of 

 blood by indirect means, is discussed under circulation time. 



The specific gravity also should be determined in a study of the 

 blood. In states of inanition the amount of blood has been observed 

 to be reduced. Obese individuals have relatively less blood. After 

 hemorrhage the blood lost is readily replaced by water, while the blood- 

 corpuscles are only gradually regenerated. After extensive, deple- 

 thoric transfusion with defibrinated blood Landois, as well as Panum, 

 observed the amount of blood and its specific gravity to be maintained. 



In the living animal Grehant and Quinquaud permitted a measured amount 

 of carbon dioxid to be inspired, then withdrew a quantity of blood and estimated 

 the amount of carbon monoxid present. From this the amount of blood can be 

 readily determined. A quantity of carbon-monoxid blood could also be transfused 

 and shortly thereafter the proportion of shed blood containing carbon monoxid, 

 and that free from carbon monoxid, be estimated. 



The estimation of the amount of blood in individual organs is made after 

 sudden ligation of their veins during life. The organs are cut up into small pieces 

 and the amount of blood contained in the wash-water is determined by comparison 

 with a specimen of blood to be diluted. The estimation after death in a state 

 of freezing is to be rejected. 



ABNORMAL INCREASE IN THE AMOUNT OF BLOOD OR ITS 



INDIVIDUAL PARTS. 



An increase in the total mass of blood uniformly in all its parts is known as 

 polyemia or plethora. It may occur as a morbid manifestation in individuals with 

 excessive nutritive and assimilative activity. A marked bluish-red color of the 

 external integument, with swollen veins and large arteries and a hard and full 

 pulse, injection particularly of the capillaries and smaller vessels of the visible 

 mucous membranes are the readily explicable signs, accompanied by cerebral 

 hyperemia, which may give rise to attacks of vertigo, and hyperemia of the lungs, 

 which may give rise to dyspnea. Also after amputation of large portions of the 

 extremities, with avoidance of loss of blood, a relative increase in the amount of 

 blood has been described (plethora apocoptica) . 



Polyemia can be induced artificially by injection of blood from the same 

 species. If the normal amount of blood be increased up to 83 per cent, no ab- 

 normal condition develops; in particular, the blood-pressure does not become 

 permanently raised. The blood finds its way especially into the greatly distended 

 capillaries, which as a result become stretched beyond their normal elasticity. 

 An increase in the amount of blood, however, up to 150 per cent, jeopardizes life 

 directly, with considerable variations in blood-pressure, and which Landois has 

 observed to terminate fatally in consequence of direct rupture of vessels. 



Following upon the injection of blood the formation of lymph rapidly in- 

 creases. Then the serum is disposed of in the course of one or two days, the 

 water being eliminated principally through the urine, and the proteids in part 

 converted into urea. Therefore, the blood at this time appears to be richer in 

 red blood-corpuscles. The red blood-corpuscles undergo destruction much more 

 slowly and the materials furnished by them are converted in part into urea and 

 in part into the biliary pigment, though not constantly. Nevertheless an excess 

 of red blood-corpuscles may be observed for as long as a month. 



That as a matter of fact the blood-corpuscles are slowly destroyed in the 

 process of metabolism is shown from the circumstance that the formation of urea 

 is greater when the animal ingests the same amount of blood than if it receives 

 an equal amount by transfusion. In the latter event a moderate increase in 



