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terminal knot and two elliptical capsules in which 

 the pollen is produced. The female flowers have 

 a stouter axis which normally produces two seeds 

 at the apex. The seed is encased in a green fleshy 

 substance and, as in the fruit of a cherry or plum, 

 the kernel is protected by a hard w^oody shell. In 

 the form of the leaves and in the structure of the 

 flowers Ginkgo presents features which clearly dis- 

 tinguish it from the Conifers, the class in w^hich, 

 until recently, it w^as included. In 1896 the Japanese 

 botanist Hirase made the important discovery that 

 the male reproductive cells of Ginkgo are large 

 motile bodies provided Avith a spirally coiled band 

 of minute cilia — delicate hairs which by their 

 rapid lashing-movement propel the cell through 

 water. In all Flow ering Plants and in Conifers the 

 male reproductive cells have no independent means 

 of locomotion ; they are carried to the female cell 

 by the formation of a slender tube — the pollen-tube — 

 produced by the pollen-grain. In the Ferns, Lyco- 

 pods and Horsetails — in fact in all members of 

 the Pteridophyta — as also in the Mosses and Liver- 

 worts as well as in many of the still lower plants, the 

 male cells swim to the egg by the lashing of cilia 

 like those on the male cells of Ginkgo. This difference 

 in regard to the nature of the male cells was con- 

 sidered to be a fundamental distinction between the 

 higher seed-bearing plants and all other groups of 



