CHAPTER LV 





NEW ORGANISMS 



338. Reproduction. One of the common facts about life is 

 that the hfe of every organism comes to an end sooner or 

 later. Yet the species, ^ 

 or kind, may continue j^ .^i 

 to live for centuries. '" 

 This is explained, of 

 course, by the fact 

 that new individuals 

 are constantly being 

 produced. The proc- 

 ess by which organ- 

 isms give rise to new 

 individuals is called 

 reprochiction. 



The term reproduc- 

 tion carries the idea 

 of a special portion of 

 the parent organism 

 being separated and 

 developing into an in- 

 dividual. The simplest 



case of which we know is that of a cell division among one- 

 celled plants or animals. When such an organism (for example, 

 a Paramecium, or a Pleurococcus cell, or some bacterium) divides 

 into two, it at the same time reproduces. The number of indi- 

 viduals is thus multiplied by a process of division, or cell fission. 

 Cell division resulting in the multiplication of individuals occurs 

 among nearly all one-celled plants and animals. 



291 



Fig. 124. Yeast plant 



The cells of this plant multiply by pushing out buds. 

 Under certain conditions the protoplasm of a cell 

 divides into two and then four parts, which then can 

 remain inactive for an indefinite time. These resting 

 cells are called spores 



