VEGETATIVE REPRODUCTION 346 



one chromosome derived originally from each parent. 

 The one from the original pollen parent is called paternal, 

 and the one from the original seed parent maternal. The 

 members of each pair are very similar though the different 

 pairs differ much from one another. When the paired 

 chromosomes arrange themselves at the middle of the 

 spindle it is a matter of chance whether the maternal or 

 the paternal one is turned toward any particular pole. 

 Next the members are drawn apart along the spindle 

 fibres. This separation of the respective maternal chro- 

 mosomes from their paternal fellows is known as segrega- 

 tion. It is also spoken of as reduction. Both features 

 are important. Reduction in number to one-half keeps 

 the chromosome number constant, generation after gen- 

 eration, and segregation gives the spores a new assort- 

 ment, a matter of great importance in heredity. 



Vegetative Reproduction is very common in plants. 

 There are many ways of accomplishing it, according to 

 the structure of particular plants. A potato, for example, 

 produces underground stems which become enlarged and 

 filled with stored food, chiefly starch. When the plant 

 matures and dies they are either harvested by man for his 

 own use or remain in the ground, in the case of wild 

 plants. In either event they will begin to grow on the 

 resumption of favorable weather and soil conditions. 

 New shoots will be put out from the leaf axils, popularly 

 called eyes, and roots from the basal portions of the 

 shoots, thus giving rise to new plants. Bulbs put out 

 side branches which develop new bulbs that are used to 

 start new plants. Rootstocks of Iris are merely prostrate 

 stems. They may be divided and used to start new 

 plants because each piece will produce new roots and 

 shoots. Dahlia roots may be used in the same way. A 

 twig of a willow may be cut and stuck into moist soil 

 where it will put out roots and grow into a tree. A twig 

 of a peach tree may be cut and grafted into another tree 

 where it will not only continue growth but also unite its 



