264 AGRoxo.MY 



pollinating agencies. In pollinating the flower the ripe anther 

 is crushed to expose the pollen, which is then thickly applied 

 to the waiting stigmas. Fresh pollen is always best, but 



in a few cases, especially in 

 orchids, it may remain alive 

 for months. After pollination 

 the flower is once more cov- 

 ered with the paper . bag 

 until the stigma is no longer 

 receptive and the ovary has 

 begun to increase in size. In 

 FIG. 102. Longitudinal section of all plants that bear both kinds 

 flower and another prepared for c -i a 



f OrallS m the Same fl W6r 



pollination 



two crosses can be made, the 



stamens of one plant supplying pollen for the other, and 

 vice versa. Sometimes a considerable difference exists in the 

 progeny of the two crosses, though usually there is practi- 

 cally none. 



Mendel's law. About half a century ago an Austrian monk 

 named Gregory Mendel, while experimenting with different 

 strains of peas in the monastery garden, discovered the curious 

 law that governs the union of male and female elements by 

 which hybrids are produced. An account of his experiments 

 was published at the time, but the significance of the results 

 did not impress the botanists of his day, and it was not until 

 1900, when the law was again independently discovered, that 

 the importance of Mendel's work was recognized and the origi- 

 nal experimenter given proper credit. Briefly the law is this : 

 when two species, or forms, are crossed, the resulting hybrids 

 tend to resemble one parent to the exclusion of the other. 

 Thus if a red-flowered and a white-flowered form be crossed, 

 the next generation is likely to have all red or all white 

 flowers. If the flowers are red, we say the red color is dominant 

 and the white recessive; or if the flowers are white, the red is 



