'THE CIRCULATION 



147 



a pearl button that has not been perforated. In freshly-drawn 

 blood they show a disposition to arrange themselves in little 

 rolls like coins (Fig. 33). 



6. The size and shape of blood corpuscles vary in different 

 animals. In man they are circular and flat, with a central 

 depression on both sides, also in all warm-blooded quadrupeds, 

 except the camel and lama, where they are oval. In birds, 

 reptiles, and fish, they are oval, but with 



raised centre or nucleus. This variation is p = 



often of vital importance in murder trials, ^ 



where blood-stained weapons or clothing are a % 



used as evidence. A microscopical examina- 

 tion shows us the corpuscles, and we deter- 

 mine from their shape, whether it was caused 

 by blood from a warm-blooded quadruped, 

 from a camel, or from a fowl or fish. But 

 we cannot affirm that the stain was made by 

 human blood, and not by that of the dog, ox, 

 or sheep, because in all of these the corpuscles 

 are shaped alike, and the size varies but little. 



7. The character of the blood of dead, ex- 

 tinct, and even fossil animals, such as the Corpuscles of a frog, c, 



, ' . . J . , . . , . . Those of a shark 



mastodon, has been ascertained by obtaining T he five small ones at 

 and examining traces of it which had been * e u PP er P art f * he 



figure, represent the hu- 



shut up, perhaps for ages, in the circulatory man corpuscles magni- 

 canals of bone. A means of detecting blood fl< 

 in minute quantities is found in the spectroscope, the same 

 instrument by which the constitution of the heavenly bodies 

 has been studied. If a solution containing not more than one 

 one-thousandth part of a grain of the coloring matter of the 

 corpuscle be examined, this instrument will detect it. 



8. The corpuscles just described are known as the red-blood 

 corpuscles. Besides these, and floating along in the same 

 plasma, are the white corpuscles. These are fewer in number, 



6. The size and shape of the corpuscles ? Why is the fact important ? 



7. The character of the blood of dead animals ? Means of detecting such blood ? 



8. White corpuscles ? Total number of corpuscles in the body ? 



Oval 

 Corpuscles of a fowl. 6, 



