86 GENERAL BIOLOGY 



Glucose + Potassium = Asparagin + Potassium + Water 4- Oxy- 

 nitrate oxalate gen 



C,H,,0, + 2KNO3 = C^N3N,03 + K,C,0, + 2Hfi + 3O 



The mineral nitrates, sulphates, phosphates, etc., enter 

 into succeeding combinations. 



Few proteins have been successfully analyzed; but it is 

 well known that many of them are of exceedingly complex 

 structure. Their molecules are composed of a very large 

 number of atoms, in loose combination. As the size of the 

 molecule increases, the stability decreases, as bricks incline 

 to topple when piled too high. A sample analysis of the 

 molecule of a familiar protein, hcemoglobin, from the 

 blood, gives results corresponding to the following formula: 



C6o»H,,„N,,,Fe,S3 0,„. 



The reverse process, whereby these complex and unstable 

 compounds are broken up again into simpler ones with the 

 liberation of their energy for the use of the body, is even less 

 understood in its details : it is chiefly known by its results. 

 The end products of metabolism in animals are water, 

 carbon dioxide, urea (CH^ N^O) uric acid (C^H^N^ O^) and 

 such other simple nitrogen compounds as ammonia, adenin, 

 xanthin, creatin, etc.; and in plants they are the same ex- 

 cept that the nitrogen liberated by proteid dissimilation is 

 recombined and does not appear as waste. The accompany- 

 ing crude diagram is an attempt to represent graphically the 

 relations the more important of these compounds bear to 

 each other in income and outgo of matter for organisms. 

 It is as the map of a country as yet but little explored. 



