EFFETE PRODUCTS. 67 



body being discharged along with the effete portions of the bile. 

 It may be recognized by the shape of the crystals, which are rhom- 

 bic plates, in which one corner is generally deficient. 



Effete Products. 



These, as has been stated before, are generally the outcome of 

 the active chemical changes necessary for the growth and vitality . 

 of the living protoplasm, and are for the most part soon eliminated 

 by the excretory glands, so that but small quantities of them can 

 be found in the active tissues where they are produced. 



Urea, CO(NH 2 ) 2 , is the most important constituent of the urine 

 of mammalia, but not of that of birds or reptiles. Traces of it 

 may be found in the fluids and tissues of the body. It is readily 

 soluble in water and alcohol, and forms crystals when its solution 

 is concentrated. It decomposes when treated with some strong 

 acids or alkalies, taking up water and yielding CO 2 and NH 8 , 

 and with nitrous acid gives CO 2 +N + H 2 O. It was the first of 

 the so-called " organic" compounds to be made artificially, being 

 obtained in 1828 by mixing watery solutions of cyan ate of potas- 

 sium and sulphate of ammonium, evaporating to dryness and ex- 

 tracting with alcohol, or in short by heating cyanate of ammonia 

 with which it is isomeric. 



CN ) CO" 



Ammonium Cyanate = N H 4 [ O = H 2 > N 2 = Urea. 



It can now be produced artificially in other ways. 



It has also been considered to be a diamide of carbonic acid 

 (CO(OH) 2 ), the two atoms of hydroxyl being replaced by two 

 atoms of amidogen, NH 2 , thus (CO(NH 2 ) 2 ). In the presence 

 of septic agencies, in a watery solution, urea takes up two atoms 

 of water and is converted into carbonate of ammonium 



CO(NH 2 ) 2 + 2H 2 = CO(ONH 4 ) 2 . 



The so-called alkaline fermentation of urine depends upon this 

 change. The reader is referred to the Chapter on Excretions, 

 where more complete information is given. 



Kreatin, C 4 H 9 N 3 O 2 , occurs in muscle and many other textures. 



