General Survey 19 



become personally intimate with particular amoebae or in- 

 fusoria ; to control their goings out and comings in ; their 

 diet and personal habits; to interfere with their social and 

 domestic relations ; to feed them and mate them ; to make 

 them do and live as we want them to live, this is what 

 we have to do if we are to really understand their lives, 

 their behavior, their growth, their matings, their heredity, 

 their evolution. 



Some years ago I devoted myself to obtaining an intimate 

 personal acquaintance with the life and behavior of indi- 

 viduals among these creatures ; to study of their individual 

 biography and perhaps psychology. I had the honor to 

 present this to the public in a book on the Behavior of 

 Lower Organisms. Building on the experience thus gained, 

 I have since devoted myself to what happens in the passage 

 of generations in these creatures ; to a study of the biology 

 of races rather than of individuals; to life, death, mating, 

 generation, heredity, variation and evolution in the Protista. 

 I am going to attempt to present a picture of these matters 

 so far as our present knowledge makes possible. We shall 

 find that there are still many questions which are not yet 

 answered, but unsolved problems after all have their fascina- 

 tion ; and much has been learned ; this I shall try to present 

 and compare with what is known for higher organisms. 



When we follow the lives of particular individuals in the 

 miniature jungle which a protozoan culture presents, we 

 come upon a fact that is most astonishing to one who knows 

 only the higher organisms. The creatures seem never to 

 die, save by accident. If we follow a single individual, we 

 find that after a time he divides into two (Figure 4). 

 Which is the parent, which the offspring? Each of these 

 again divides into two, and this continues for generation 

 after generation. Nowhere does a corpse appear; nothing 



