PART 111: REPRODUCTION. 



CHAPTER XVI. 



INTRODUCTION, 



Having considered in Parts I and II the structures and 

 functions by which the nutrition of the individual is secured, 

 Part III is devoted to the consideration of the structure and 

 functions of the reproductive organs and the functions by 

 which a succession of similar individuals is insured. 



One of the fundamental powers of protoplasm is its ability 

 to produce new organisms as offspring from the older ones. 

 In the simpler plants the two great functions, nutrition and 

 reproduction, are often carried on bv the same cell. This 

 must alwavs be so in the unicellular plants. In the higher 

 plants, ho\ve\'er, these two functions become completeU" seii- 

 arated, oi-gans being specialized for each, so that the func- 

 tions mav be more certainlv and efticientlv performed. 



299. Reproductive structures. — Any part capalile of grow- 

 ing into a new indi\"idual mav lie called a reproductive body, and 

 the I'lart on which or in which it is jM-oduted is a reproduclive 

 organ. If the reproducti"\"e bodies consist of one or two cells 

 only, thev are usually called spores. If they are cell-aggre- 

 gates, thev are generallv called brood buds or gemmce, to dis- 

 tinguish them from ordinarv buds. In both lases it is neces- 

 sarv that the cells to be se])arated from the parent should be 

 capable of gro\Mh — that is, in the condition known as the 

 embr\-onic phase {^ 256). The reprodiicti\"e organs pro- 



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