56 THE BLOOD. 



blood-corpuscles or blood-cells. The structural composition of 

 the blood may be thus expressed : 



f Corpuscles, . . 1 Clot (containing also 



T- ,-j pi^,i f more or less serum). 



Liquid Mood, j LiqnorS anguinisC Fibrin, \ 



[ or Plasma. \Serum. 



When blood flows from the living body, it is a thickish 

 heavy fluid, of a bright scarlet color when it comes from an 

 artery; deep purple, or nearly black, when it flows from a 

 vein. Its specific gravity at 60 F. is, on an average, 1055, 

 that of water being reckoned as 1000 ; the extremes consistent 

 with health being 1050 and 1059. Its temperature is generally 

 about 100 F.; but it is not the same in all parts of the body. 

 Thus, while the stream is slightly warmed by passing through 

 the liver and some other parts, it is slightly cooled, according 

 to Bernard, by traversing the capillaries of the skin. The 

 temperature of blood in the left side of the heart is, again 1 

 or 2 higher than in the right (Savory). 



The blood has a slight alkaline reaction ; and emits an odor 

 similar to that which issues from the skin or breath of the 

 animal from which it flows, but fainter. The alkaline reac- 

 tion appears to be a constant character of blood in all animals 

 and under all circumstances. An exception has been supposed 

 to exist in the case of menstrual blood ; but the acid reaction 

 which this sometimes presents is due to the mixture of an acid 

 mucus from the uterus and vagina. Pure menstrual blood, 

 such as may be obtained with a speculum, or from the uteri 

 of women who die during menstruation, is always alkaline, 

 and resembles ordinary blood. According to Bernard, blood 

 becomes spontaneously acid after removal from the body, 

 owing to conversion of its sugar into lactic acid. 



The odor of blood is easily perceived in the watery vapor, 

 or halitus as it is called, which rises from blood just drawn : it 

 may also be set free, long afterwards, by adding to the blood 

 a mixture of equal parts of sulphuric acid and water. It is 

 said to be not difficult to tell, by the likeness of the odor to 

 that of the body, the species of domestic animal from which 

 any specimen of blood has been taken : the strong odor of the 

 pig or cat, and the peculiar milky smell of the cow, are es- 

 pecially easy to be thus discerned in their blood (Barruel). 



Quantity of Blood. 



Only an imperfect indication of the whole quantity of blood 

 in the body is afforded by measurement of that which escapes, 

 when an animal is rapidly bled to death, inasmuch as a cer- 



