PART I 



INTRODUCTION TO BIOLOGICAL STUDY 



CHAPTER I 

 BIOLOGY: THE SCIENCE OF LIFE 



1.* Living and Lifeless Things. Since the science of 

 biology deals with living things, it is of importance that at 

 the beginning of our study we should stop to consider that 

 all things which we know through our senses are either living 

 or lifeless. This will be evident if we attempt to write the 

 names of some common things, grouping them according to 

 whether they appear to have life or not. It is not difficult 

 to decide that air, soil, minerals, and water belong in the 

 list of lifeless things and that the most common animals and 

 plants are examples of the living; but we are puzzled by such 

 objects as dry seeds, undeveloped eggs of animals, some 

 plants in the winter condition, and many microscopic ani- 

 mals which show no signs of life when dry. Are such things 

 living or lifeless ? Usually it is not possible to answer until 

 time and proper conditions have given an opportunity for 

 changes which suggest life-activities. However, such uncer- 

 tain cases must be left undecided until after a careful study 

 of the differences between living and lifeless things. 



* In the "Teachers' Manual of Biology" designed to accompany this 

 book there will be found, in paragraphs numbered to correspond with those 

 in this textbook, notes on books, materials, and methods of interest to 

 teachers, or to advanced students in normal-school classes, 



B 1 



