F. THE BIOSPHERE. 



CHAPTER XXTV. 



SUBDIVISION OF THE BIOSPHERE. CLASSIFICATION AND GEN- 

 ERAL MORPHOLOGICAL CHARACTERS OF ORGANISMS. 



The organic world or biosphere falls naturally into two great 

 subdivisions or kingdoms, the phytosphere, or plant kingdom, 

 and the zoosphere, or animal kingdom, though organisms occur or 

 have occurred which are not readily placed in either division. 

 The detailed study of organisms has developed the sciences of 

 phytology (botany) and zoology, with its many subordinate sciences. 

 As ordinarily understood, these sciences deal with the plants and 

 animals of the present, or Holocenic, geological epoch, while those 

 of the many epochs of the earth's history anterior to the present 

 are reserved for the palaeontologist. Such a division, however, is 

 illogical, for the life of the earth has been continuous and its de- 

 velopment has been progressive from the earliest time to the 

 present day. The scientific palaeontologist can not neglect the study 

 of the existing organisms, nor can the scientific zoologist and botan- 

 ist, or student of the present living world, neglect the organisms of 

 the past. Pal?eozoology cannot be divorced from zoology, nor 

 palaeobotany from botany. From the nature of the organic remains 

 of former periods it follows, however, that the palaeontologist lays 

 most stress upon the hard parts of organisms, or those capable 

 of preservation, in former as well as the present geological periods, 

 while the botanist and zoologist in the study of the modern floras 

 and faunas tend to lay more stress upon the soft tissues which 

 perish readily and so are not, or only rarely, preserved in the case of 

 ancient forms of life. 



There are, however, good reasons for believing that the hard 

 parts of organisms form in some respects a more reliable index 

 to their relationship than do the soft parts. This is especially the 

 case in animals wdiich build external hard parts which increase by 

 serial addition, without change of the older parts deposited. In 



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