NORMAL QUANTITY OF BLOOD. 61 



(because ordinary blood varies in colour according to the amount of O contained in 

 it Gscheidlen, Heidenhain). Tie a | -shaped cannula in the two cut ends of the 

 carotid, and allow a 0'6 per cent, solution of common salt to flow into the vessel 

 from a pressure bottle ; collect the coloured fluid issuing from the jugular veins 

 and inferior vena cava until the fluid is quite clear. The entire body is then 

 chopped up (with the exception of the contents of the stomach and intestines, 

 which are weighed, and their weight deducted from the body- weight), and 

 extracted with water, and after twenty-four hours the fluid is expressed. This 

 water, as well as the washings with salt solution, are collected and weighed, and 

 part of the mixture is saturated with CO. A sample of this dilute blood is placed 

 in a vessel with parallel sides (1 c.m. thick), opposite the light (the so-called 

 haematinometer), and in a second vessel of the same dimensions, a sample of the 

 undiluted CO-blood is diluted with water from a burette until both fluids give 

 the same intensity of colour. From the quantity of water required to dilute the 

 blood to the tint of the washings of the blood-vessels, the quantity of blood in 

 the washings is calculated. (On chopping up the muscles alone, we obtain the 

 amount of Hb present in them, which is not taken into calculation Kiihne). 



Quantity of Blood in Various Animals. The quantity of blood in 

 the mouse = T V to -^ ; guinea-pig -^ ( T V to ^) ; ra bbit = ^ 



(A to *V) m > do s = TS (ft to A) ; cat = r* ; birds = A to A ; 



frog = ^ to ^5- ; fishes = y T to ^ of the body-weight (without the 

 contents of the stomach and intestines). 



The specific gravity of the blood ought always to be taken when 

 estimating the amount of blood. The amount of blood is diminished 

 during inanition ; fat persons have relatively less blood ; after haemorr- 

 hage the loss is at first replaced by a watery fluid, while the blood- 

 corpuscles are gradually regenerated (p. 63). 



The estimation of the quantity of blood in different organs is done by 

 suddenly ligaturing their blood-vessels intra vitam. A watery extract 

 of the chopped up organ is prepared, and the quantity of blood estimated 

 as described above. Roughly, it may be said that the lungs, heart, large 

 arteries, and veins contain J; the muscles of the skeleton, J; the 

 liver, J : and other organs, J (Ranke). 



41. Variations from the Normal Condition of 

 the Blood. 



(A.) Increase of the Blood, or of its Individual Constituents. (l.) An 



increase in the entire mass of the blood, uniformly in all organs, constitutes 

 polycemia (or plethora), and in over-nourished individuals it may approach a patho- 

 logical condition. A bluish-red colour of the skin, swollen veins, large arteries, 

 hard full pulse, injection of the capillaries and smaller vessels of the visible 

 mucous membranes are signs of this state, accompanied by congestion of the brain, 

 giving rise to vertigo, and congestion of the lungs, as shown by breathlessness. 

 After major amputations with little loss of blood a relative increase of blood has 

 been found (?) (plethora apocoptica). 



Transfusion. Poly semia may be produced artificially by the injection of blood 

 of the same species. If the normal quantity of blood be increased 83 per cent. 



