THE DIFFERENTIATION OF FLOWER-BUDS 41 



point it is not covered by the epidermis, down through the 

 style into the placontsB of the carpels to the ovules. 



"There are no traces of the ovule evident at the beginning 

 of the winter rest, nor do they appear until active growth has 

 been resumed in the spring. A small protuberance, slightly 

 below the middle of the carpel, first becomes evident, about 

 the time the winter fruit buds are swelling and almost 

 munediately a second blunter protuberance appears directly 

 below it. . . . The upper protuberance which becomes the 

 ovule develops very rapidly. At first it stands at nearly right 

 angles to the placenta from which it arises. Very soon there- 

 after, as growth progresses, it begins to assume a slightly 

 downward and outward movement away from the middle 

 line of the carpel toward the side walls. At this time the 

 initial development of the integuments, of which there are 

 two, begins. They develop at practically the same time 

 though the imier may be slightly in advance of the outer. At 

 this time the axis of the ovule no longer remains at right 

 angles to the placenta, but now forms an acute angle with it, 

 the distal end of the ovule pointing do^vnward and outward 

 toward the sides of the carpels. Thus the two ovules in 

 each locule stand back to back, so to speak, their tips point- 

 ing toward the base of the carpel. At the time the flower 

 is in full bloom the integuments entirely cover the nucellus, 

 the ovule has become completely anatropous and the micro- 

 pylar end rests against the obturator below it. The embiyo 

 sac and its contents are completely formed at this time and 

 are ready for fertilization." (See Fig. 17.) 



41. The peach, plum, and cherry. — The peach in Virginia 

 showed initial differentiation of flower-buds during the first 

 week in August. The plum varied more than other fruits in 

 the time of initial development of the flower-buds. With 

 the Japanese varieties, it was the second week in July, with 

 those of the American group it was the first week, while the 



