BLACK: INFLORESCENCE AND FRUIT OF PYRUS MALUS 527 



appear that the terminal flower was in the axil of this bract and 

 by its more vigorous development had caused the abortion or 

 complete suppression of the bract and its potential bud. From 

 the basis of the definition, a terminal flower can not be a lateral 

 structure. Therefore a terminal flower can not be axillary, be- 

 cause an axillary flower becomes, ipso facto, a lateral structure. 

 A comparison of sections of developing flowers, however, shows the 

 unmistakable terminal character of the oldest flower from the time 

 of its inception to its maturity. In plate 35, figures 4, 6, and 7 

 are of the terminal flower and show that it is a direct continuation 

 of the axis. It is more logical, from the centrifugal type of flower- 

 ing and from microscopic observation, to conclude that the axis 

 is terminated by the oldest flower and is therefore a type of cymose 

 inflorescence and may correctly be called a cyme. 



3. The flower 



The development of the flower of the apple is of two-fold interest. 

 It is a foundation for the subject of pollination and for the sub- 

 sequent formation of the fruit. Progressive stages in the develop- 

 ment of the apple flower have been described and figured by 

 many writers — Goff (8) has discussed the origin and time of 

 flower formation in the apple, as well as in the pear, plum, and 

 cherry. Drinkard (7) by means of a series of photomicrographs 

 presents stages in the development of the flower in the apple, 

 plum, pear, peach, and cherry. Quaintance (20) gives a few 

 figures in the development of the peach flower. Kraus (6) de- 

 scribes different stages in the development of apple flowers with 

 particular reference to the origin and nature of the fruit and 

 Bradford (21) shows very early stages in the flower formation 

 of a number of varieties of apples. 



The bud in plate 35, figure 2, shows the broad growing region 

 upon which the inflorescence will develop. This region consists 

 of ten or twelve rows of small, dense cells. These cells have large 

 nuclei and may be observed in various stages of cell division. 

 Below this meristematic tissue the cells are gradually differentiated 

 by their large size, irregular arrangement, and cell content. This 

 tissue is the pith and is characterized by many intercellular spaces 

 formed partly by the breaking down of one or more cells. The 

 density of the cells in this region varies considerably according to 



