16 Principles of Plant Culture. 



cells (Fig.. 1), or by the formation of new cells within 

 older ones— the young cells thus formed attaining full 

 size by subsequent enlargement. 



16. Reproduction is the increase in number of living 

 beings. It is one of the properties of protoplasm and 

 is essentially a process of division. As living cells mul- 

 tiply by forming new cells, so living beings, which con- 

 sist of cells, multiply by the separation of a part of 

 their own cells, and this separated group of cells grows 

 into a complete organism like the parent. The higher 

 plants multiply by seeds (155), which are separated 

 from the parent plant, and each of which contains a 

 young plant (53). The eggs from which young birds 

 are hatched contain cells filled with living protoplasm, 

 and the protoplasm of the living young of mammals is 

 separated from the parent before birth. Prolificacy, 

 the faculty for reproduction, depends in part upon 

 variety. 



17. Reproduction is either Sexual or Non-Sexual. 

 Sexual reproduction can take place, as a rule, only upon 

 the union of cells of different sexes. It is not peculiar 

 to the animal kingdom, but occurs in plants also, and 

 except in rare cases, is necessary to the production of 

 seeds that are capable of germination (28). It is the 

 only method of reproduction in the higher animals. 

 Sexual reproduction does not usually take place until 

 the period of most rapid growth has passed. Non- 

 sexual reproduction is independent of sex. It results 

 from the direct separation of a part of the parent, 

 which under favorable conditions develops into a com- 

 plete individual. It occurs when plants multiply by 



