XX INTRODUCTION. 



port of heat and life in every part through which it has subse- 

 quently to circulate ; experience proving to us, that deprivation 

 of blood to a part is followed first by the loss of heat, and 

 ultimately of its vitality. In what this extraordinary influence 

 of the air upon the blood consists, we are only vaguely informed : 

 in truth, we know but very little more for certain concerning it 

 than the palpable change of colour the blood undergoes, from a 

 very dark to a bright scarlet red. 



To make up for the expenditure in the quantity of blood, we 

 find a number of organs provided, comprehended under the head 

 of the DIGESTIVE SYSTEM ; the ultimate object of whosc Combined 

 operation is, the transmutation of the food into a fluid fit for 

 becoming blood. The organs concerned in the process of digestion 

 are — the mouth, in which the food is broken down and masti- 

 cated by the teeth, and at the same time mixed with saliva; the 

 'pharynx, which receives the food from the mouth, and by the 

 act of deglutition transmits it to the esophagus, the tube that 

 conducts it into the stomach. Within the stomach, the food 

 becomes converted into a uniform homogeneous mass, termed 

 chyme ; and thus becomes prepared for its further passage into 

 the intestines, in which, from the admixture of bile coming 

 from the liver, and pancreatic juice from the pancreas, a further 

 change takes place in the alimentary mass, attended by a spon- 

 taneous separation of it into such parts as are veritably nutritious, 

 and such as are excrementitious, or only fit for being ejected out 

 of the body. The nutritious particles assume the appearance of a 

 milky juice, to which anatomists have given the name o^ chyle ; and 

 the process by which it is produced is denominated chylijicatiun. 



This brings us to the consideration of the ABSORBENT system : 

 the absorbent vessels being the conductors of the chyle from the 

 cavity of the intestines into the veins, in which it becomes 

 mingled with the general mass of blood. Independently of this, 

 however, the absorbents are employed in removing old, decayed, 

 or worn-out parts of the body, at the time that the arteries 

 are restoring the loss by the deposition of new material ; so that, 

 in point of fact, the body is undergoing a continual repair, or 

 rather renovation, and thus is maintained in perpetual vigour and 

 aptitude for action. 



