114 PHYSIOLOGY AND HEALTH. 



yesterday. Perhaps we have not now an atom of the flesh 

 that we had ten years ago. 



247. Though the individual atoms change, the whole, the 

 totality, remains unchanged. The new atoms have the same 

 character, the same sympathies, and perform the same func- 

 tions, as those that went before them. The animal body, in 

 this respect, is like a community, or a town of a definite 

 number of people. The individual members of this commu- 

 nity are continually changing; some go out to other towns 

 some die; but their places are filled by others that come 

 from abroad, and by some that are born. The individuals 

 are not all the same from year to year ; and, in course of a 

 single generation, they are all exchanged ; and yet the body, 

 the town, remains unchanged. The same character and 

 habits are there, the same principles govern them. The 

 community is, in fact, the same, even after every one of its 

 original component elements has been removed and replaced 

 by others. 



248. The experiment has been tried of feeding pigs and 

 sheep upon madder, which is a pink coloring matter. 

 When some of these animals were killed, while they were 

 living upon this food, the bones were found to be tinged with 

 red. But some others were kept, for the same time, upon 

 madder, and afterwards were fed, for a period, with hay and 

 grain ; then being killed, their bones were found to be as 

 white as those of animals which had never eaten madder. 

 There is no doubt that the bones of these last animals had 

 been stained with the madder while they lived upon it, and 

 that they became white when they again were fed on other 

 food. 



249. This is easily explained by the action of their nutri- 

 ent and absorbent systems. The coloring matter of the 

 madder was carried in the chyle to the blood, and in the 

 blood to the bone, and there deposited ; and, when this is 

 absorbed, more red matter is brought and left there; and this 

 continues as long as madder is eaten. But, when the food is 

 changed, no more red matter is carried to the bones, and 



