INTRODUCTION 7 



There are various methods of producing more life, 

 given a nest-egg of living substance with which to 

 start. Any organism, whether plant or animal, is 

 continually transforming inorganic and dead material 

 into living tissue. Through the process of repair, 

 for example, an injury to a form as highly developed 

 even as man is frequently made good, if it is not too 

 extensive, as in the case of a skin wound. 



When the intake of non-living material is in excess 

 of the outgo, growth results, with the consequence 

 that more living substance is built up than existed 

 before. Thus a fragment of a living sponge or a 

 piece of a begonia leaf are each sufficient to restore a 

 duplicate of the original organism. 



A process similar to the repair of the begonia leaf 

 is that employed so effectively in the great groups of 

 the one-celled animals and plants, the Protozoa and 

 Protophyta, by means of which their numbers are 

 maintained. These one-celled organisms multiply 

 by fission, that is, by equal division into halves, and 

 each half then grows to the size of the parent organism 

 from which it sprang. When two daughter pro- 

 tozoans are thus formed, they are essentially orphans 

 because they have no parents, alive or dead. The 

 parental substance in such a process, along with the 

 regulating power necessary to reorganization, goes 

 over bodily into the next generation in the forma- 

 tion of the daughter-cells, leaving usually no re- 

 mains whatever behind.' In primitive forms of this 

 description, continuous life is the natural order, 

 and death, when it does occur, is, as Weismann has 



