. Plant life, considered with special references to form and function. Plant physiology. Fig. 317. Fig. 31S. Fig. 317.âGametoph\'te of the pinesap (Mojiotropa Hy/-opitys\. a. microspore show- ing two cells; the smaller being the sperm cell and the larger corresponding to the wall of the spermary, undivided. /â . the same, 6 hours later, shoi.\-ing the pollen tube de\"eloped from the larger cell. The smaller one has become disorganized and its nucleus (still undi\-ided into spermsi and that of the larger cell have migrated into the tube. Magnihed 600 diam.^After Strasburger. Fig. 318. âOne
. Plant life, considered with special references to form and function. Plant physiology. Fig. 317. Fig. 31S. Fig. 317.âGametoph\'te of the pinesap (Mojiotropa Hy/-opitys\. a. microspore show- ing two cells; the smaller being the sperm cell and the larger corresponding to the wall of the spermary, undivided. /â . the same, 6 hours later, shoi.\-ing the pollen tube de\"eloped from the larger cell. The smaller one has become disorganized and its nucleus (still undi\-ided into spermsi and that of the larger cell have migrated into the tube. Magnihed 600 diam.^After Strasburger. Fig. 318. âOne stage in the fertilization of the i:%% of an orchid (Orchis latifolia'). The pollen tube, /, has entered the narrow micropyle, ju, of an o\'ule. and reached the megaspore e, the upper lialf of which only is shown ^^^th three eggs (two imperfectt. In the pollen tube, just above and below the entrance of the micropvle, are the two sperms, s^ s'. Magnified 360 diam.âAfter Strasburger. Fig. 319.âLongitudinal section through the ovule of the larch and the placental scale to which it is attached, y, placental scale ; ,t,', vascular bundles : ;/. megasporangium ; /, integument; c'. female gametoph\'te inside megaspore whose limit is sho\\n by oval line ; a, ov^ry;/, pollen-tube. Magnified 14 diam,âAfter Strasburger. The growth of the spermary as a tube within wliich the sperms may migrate to the egg is necessary because the female gametophyte is forced to de\'elop within the megaspore, which is not released from the sporangium. In angiosperms the further enclosure of the megasporangia in the sporophyll (carpel) makes it necessary for the tube to be sufficiently long. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Barnes, Charles Reid, 1858-1910. New York, H. Holt & company
Size: 1181px × 2116px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., book, bookcentury1800, bookdecade1890, booksubjectplantphysiology
