532 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



to be caused by the growth of any special cell but is due to the 

 growth of several cells. It results in a somewhat rounded pro- 

 tuberance just below the micropylar end of the ovule (plate 39, 

 FIGURES I and 5). The nucellus of the ovule is conspicuous from 

 the first. The ovule shows its anatropous character at an early 

 stage. This is seen in plate 38, figure 3, as are also the integu- 

 ments. Both inner and outer integuments show on the free sur- 

 face of the ovule. The macrospore is apparent as a large cell two 

 or three cell rows below the surface in favorable sections of ovules 

 of this stage. A mature ovule is shown in plate 39, figure 

 I. The integuments have closed over the nucellus, leaving a 

 narrow micropyle. A well-developed nucellar tissue surrounds 

 the embryo-sac, which is situated six or seven cell rows below the 

 nucellar cap. The integument on the inner side of the ovule is ad- 

 jacent with the funiculus and the latter arises just above the 

 spongy obturator. The fibro-vascular strand in the funiculus 

 terminates in a well-marked chalaza, which is particularly pro- 

 minent as the ovule matures. The chalaza is conspicuous in the 

 three ovules in figure 2, plate 39, as shown in the cross section 

 at the base of the integument. 



The macrospore gives rise to a seven-celled embryo-sac, the 

 micropylar end of which is broader than the opposite end. The 

 Qgg apparatus is well developed. The three antipodal cells are 

 found in the somewhat pointed end of the embryo-sac. The micro- 

 pylar polar nucleus and the antipodal polar nucleus fuse, forming 

 the endosperm or fusion nucleus. 



4. Pollination and fertilization 

 The pollination of members of the Pomaceae has been described in 

 two articles by Waite (24, 25) and in the apple by Lewis (26). The 

 subject of pollination has been studied from various points of view 

 and there is an extensive literature upon the subject. A discussion 

 of it here seems unnecessary. Flowers were hand-pollinated with 

 pollen from Baldwin flowers and with the pollen from other varie- 

 ties. The Baldwin is evidently more or less self-sterile, as a greater 

 percent of fruit was secured from the flowers pollinated with pollen 

 from other trees than with Baldwin pollen. Pollination in the 

 Baldwin ajjple is dependent more upon bees and insects than the 

 wind. This was indicated by the greater number of fruits set in 



