4 DESCRIPTION OF THE BLOOD. 



the body are formed from the blood ; and therefore to give a full description of that fluid 

 would occupy more space than can be afforded to one subject. It is, however, so important a 

 substance that it demands some notice. 



When it is freshly drawn, the blood appears to be of a uniform consistence, but if poured 

 into a vessel and suffered to remain undisturbed it soon begins to change its aspect. A com- 

 paratively solid and curd-like mass, of a deep red color, rises to the surface, and there forms a 

 kind of cake, while the liquid on which it floats is limpid and almost colorless. The solid 

 mass is called the clot, and the liquid is known by the name of serum. The whole time con- 

 sumed in this curious process is about twenty minutes. While thus coagulating the blood 

 gives out a peculiar odor, which, although far from powerful, can be perceived at some distance, 

 and to many persons is inexpressibly revolting. 



The upper part of the clot is covered with a thick film of an elastic and tenacious nature, 

 which can be washed free from the red coloring substance, and then appears of a yellowish 

 white tint. It can be drawn out and spread between the fingers, as if it were an organic mem- 

 brane ; and, as its particles arrange themselves into fibres, the substance is called fibrin. 

 When a portion of fibrin is drawn out until it is much lengthened, the fibres are seen crossing 

 each other in all directions, sometimes forming themselves into regular lines. 



The red mass, which remains after the fibrin and serum have been removed, is almost wholly 

 composed of myriads of small rounded bodies, called corpuscules, which can be readily seen 

 by spreading a drop of blood very thinly on glass, and examining it with a microscope. 

 Some of the disc-like corpuscules are seen scattered about, while others have run together and 

 adhered by their flat sides, until they look somewhat like rouleaux of coin. There is sufficient 

 distinction between the blood corpuscules of the various Mammalia to indicate to a practised 

 eye the kind of animal from which they were taken ; while the blood of the four great divisions 

 of the Vertebrates is so strongly marked, that a casual glance will detect the ownership of the 

 object under the microscope. The blood corpuscules of the Mammalia are circular, while those 

 of the other three divisions are more or less elliptical. 



That the blood contains within itself the various substances of which the body is composed, 

 is evident to the intellect, although as yet no investigator has discovered the mode of its 

 operation. 



How the blood corpuscules are generated from the vegetable and animal substances taken 

 into the stomach, we know not ; but we do know that each globule possesses life, passing 

 through its regular stages of birth, development, age, and death. When yet in their first 

 stages of existence, the blood corpuscules are colorless, not taking the well-known ruddy tint 

 until they have attained their full development. The living current that passes through our 

 bodies is truly a fathomless ocean of wonders ! Even the material formation of this fluid is 

 beyond our present sight, which cannot penetrate through the veil which conceals its mysteries. 

 Much less can we explain the connection of the blood with the mind, or know how it is that 

 one thought will send the blood coursing through the frame with furious speed, crimsoning 

 the face with hot blushes ; or another cause the vital fluid to recoil to the heart, leaving the 

 countenance pallid, the eyes vacant, and the limbs cold and powerless, as if the very life had 

 departed from the body. 



Not without reason do the earlier Scriptures speak so reverently of the blood, 

 accepting the outpoured life of beasts as an atonement for the sin, and witness of the 

 penitence of man, and forbid its use for any less sacred office. Nor was it without a still 

 mightier meaning that the later Scriptures endue the blood with a sacramental sense, giving 

 even to its vegetable symbol, the blood of the grape, a dignity greater than that of the former 

 sacrifices. 



A few words must also be given to the mode by which the blood is kept continually run- 

 ning its appointed course through the animal frame. This process, commonly called CIRCULA- 

 TION, takes place in the following manner, Man being an example : 



In the centre of the breast lies the heart, an organ composed of four chambers, the two 

 upper being termed auricles, and the two lower being distinguished by the title of ventricles. 

 These are only conventional terms, and do not express the office of the parts. The auricles are 



