THE PRINCIPLES OF BIOLOGY 



INTRODUCTION 



1. Biology is the science which treats of living things, or of 

 objects having life. In the broad application of the term, as 

 used here, Biology includes a number of more special sciences. 

 Morphology, Anatomy and Histology treat of form and struc- 

 ture. On the other hand, Physiology deals primarily with the 

 function of organs. In Embryology it is the development of 

 the individual, especially during the earlier stages, that is kept 

 chiefly in view. Paleontology treats only of fossils, that is, those 

 types of living things which existed at some earlier period in 

 the world's history but which have now become extinct. 



2. Even with such a sub-division of the subject we have 

 left special sciences which cover such a broad field that they 

 become unwieldly. In Botany and Zoology the subject is 

 divided on the basis of the kinds of living things considered, 

 the former being the biology of plants, the latter the biology 

 of animals. Still further sub-division leads to Cryptogamic 

 Botany, Phanerogamic Botany, Invertebrate Zoology and 

 Vertebrate Zoology. Bacteriology, Entomology (insect zool- 

 ogy), Ornithology (bird zoology), and still other more narrowly 

 restricted branches of biology are recognized. The very ex- 

 tensive study of man has given rise to a number of biological 

 sciences dealing only with this single genus; viz., Human 

 Anatomy, Human Physiology, Human Embryology, Anthro- 

 pology (dealing with the comparative anatomy of the various 



