THE NATURAL SYSTEM. 



This classification will be found useful in physiological discus- 

 sions, but does not represent relationship in the sense of commu- 

 nity of descent. For example, there are certain fungi which are 

 very closely similar in structure to green plants, and have prob- 

 ably shared their ancestral origin. But if they ever had the 

 power of utilizing the energy of sunlight in constructing complex 

 food, they have lost it, and hence must be assigned to an entirely 

 different physiological group. 



In the detailed study of the relationships of plants and ani- 

 mals it is necessary to adopt a classification based as nearly as 

 our knowledge will permit upon the resemblances due to com- 

 munity of descent. For the sake of convenient reference the 

 classification here adopted and shown in the following table is 

 nearly identical with that of two leading authorities in Botany 

 and Zoology, viz., Sachs and Glaus, to whose w r orks the student 

 is referred for further details. 



