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MORPHOLOGY OF ANGIOSPERMS 



the pollen-grain with its pollen-tube and some contents, as well 

 as the ovule with its integuments and embryo-sac; and the 

 pollen-tube had been traced from the stigma to the embryo-sac. 



FIG. 65. A- C, Orchis Morio\ D, O. latifolia; E, 0. maculata; F, Canna limbata. 

 A-B, young ovules, x 150; (7, end of pollen-tube enlarging, x 100; Z>, later stage 

 with two nuclei visible in embryo, x 166; E, more advanced embryo, x 208; F, 

 considerably later stage, x 125. After SCHACHT.! 



In 1835 Schleiden, the founder of the cell-theory, traced 

 the pollen-tube in a large number of widely separated families. 

 He claimed to have seen the tube enter the micropyle, press into 

 the embryo-sac, and then become itself the embryonal vesicle, 

 the beginning of the embryo. He thought that the contents of 

 the pollen-tube not only give rise to the embryonal vesicle, but 

 that the end of the tube, nourished by the embryo-sac, becomes 

 the future plant. 



