PART III: 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 by the same cell. This 

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

 plants, however, these two functions become completely sep- 

 arated, organs being specialized for each, so that the func- 

 tions may be more certainly and efficiently performed. 



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

 ing into a new individual may be called a reproductive body, and 

 the part on which or in which it is produced is a reproductive 

 organ. If the reproductive bodies consist of one or two cells 

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

 gates, they are generally called brood buds or gemmce, to dis- 

 tinguish them from ordinary buds. In both cases it is neces- 

 sary that the cells to be separated from the parent should be 

 capable of growth — that is, in the condition known as the 

 embryonic phase (•[[ 256). The reproductive organs pro- 



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