290 PHYSIOLOGY. 



rounded form ; and the fluids they secrete, are very different 

 from each other, and also from the blood which furnishes the 

 same materials to all. For instance, the liver secretes the 

 yellow, ropy fluid, called bile ; the kidneys, secrete urine ; the 

 lachrymal gland, which is placed immediately over the eye 

 in the orbit, secretes the tears ; and the spittle or saliva is 

 poured out from the salivary glands. 



18. ( Glands are formed of a large number of arteries, veins, 

 nerves, and lymphatics, disposed in a peculiar manner, and 

 connected together by a tissue of cellular membrane) When 

 in a cavity, they are covered on their external surface by a 

 coat, derived from the membrane that lines the cavity, and 

 they are also provided with a canal, called excretory duct, 

 which is lined with mucous membrane. There are seven 

 kinds of glandular secretions. 



19. The secreted fluids have been divided |into serous or 

 watery, albuminous mucous, oily, and the mixed j( such as sa- 

 liva, bile, tears, dec. They have also been divided into recre- 

 mentitious and the excrementitious, or those which are des- 

 tined to be absorbed and returned into the mass of the blood, 

 and which are deposited in cavities that have no external 

 opening ; and the second, those which are designed, after 

 their formation, to be expelled from the system. 



20. When any substance is taken up by the absorbents, 

 and carried into the blood, which cannot be converted to any 

 useful purpose in the system/it is immediately discharged by 

 means of the secretions. Not many years ago, a man was 

 carried into a London hospital, who was picked up drunk in 

 the streets. He lived but a short time, and on examining 

 his brain, nearly a half a gill of fluid strongly impregnated 

 with gin, was found in the ventricles. This was secreted. 



21. Unless the secretions all go on, we cannot enjoy good 

 health. If that from the skin is stopped, fever, or some in- 

 ternal inflammation is the consequence. If the bile ceases 

 to flow, we cannot properly digest our food ; and so if any 

 of the others are interrupted, some serious disease will be the 



