THE ORGANS OF EXCRETION 266 



it to be when alcohol is introduced into the circulation 

 and uses up the oxygen which should be applied to the 

 oxidation of food, then the weight may increase, but it 

 is by the retention of poisonous matter which ought to 

 be removed. No other one cause creates so much disease of 

 the kidneys as does the use of alcohol. Imperfect oxida- 

 tion of food develops poisons which the kidneys are 

 overtaxed to remove. This may be caused by eating too 

 much, or by eating unwholesome food, or too much of 

 certain kinds of food, as sugar especially; or it may be 

 caused by alcohol. " Fatty degeneration of the kidneys " 

 is a frequent result of the use of alcoholic drinks. The 

 cells of the tissues become so altered, also, that they fail 

 to act normally by removing only the poisonous sub- 

 stances, and they allow the valuable elements in the blood 

 to be drained off with the waste. This is seen in the 

 serious disease called " Bright's disease " in which the 

 albumin which is necessary to health is excreted by 

 the kidneys. 



DEMONSTRATIONS 



123. Dissection of the Kidney. Procure a kidney of a sheep or of 

 a pig. As much as possible of the ureter should remain attached. 

 The kidney is seen to be inclosed in a capsule. Remove the latter, 

 and notice the shape of the kidney and the enlarged attachment of 

 the ureter. Split the kidney lengthwise parallel to the broad surface, 

 and observe on the outside of the section a layer, the cortical layer, 

 differing in color from the more internal, medullary, portions. Notice 

 the projections, pyramids, of the medullary portion into the sinus. 

 The latter is a cavity in the concave side of the organ, continuous 

 with the cavity of the ureter. 



124. Minute Structure of the Kidney. For this some prepared sec- 

 tions will be needed: (1) section showing general structure of cortex 

 and medulla, with uriniferous tubules plainly demonstrated ; (2) sec- 

 tion showing blood vessels injected ; (3) a cross section of the ureter. 



