204 GENETICS 



though it may be extended to clones, parthenogenetic 

 lines and to homozygous crosses. 



A quotation from the memoirs of the Manchu em- 

 peror K'ang-Hsi, 1662-1723, translated from VEm- 

 pire Chinois, E. R. Hue, will illustrate an early 

 application of the pedigree method. "On the first day 

 of the sixth moon I was walking in some fields where 

 rice had been sown to be ready for the harvest in the 

 ninth moon. I observed by chance a stalk of rice 

 already in ear. It was higher than all the rest and 

 ripe enough to be gathered. I ordered it brought to 

 me. The grain was very fine and well grown, which 

 gave me the idea to keep it for a trial and see if the 

 following year it would preserve its precocity. It 

 did so. All the stalks which came from it showed ear 

 before the usual time and were ripe in the sixth moon. 

 Each year has multiplied the produce of the preceding, 

 and for thirty years it is the rice which has been 

 served at my table. It is the only sort which can ripen 

 north of the great wall, where the winter ends late and 

 begins very early ; but in the southern provinces, where 

 the climate is milder and the land more fertile, two 

 harvests a year may be easily obtained, and it is for 

 me a sweet rejection to have procured this advantage 

 for my people" 



In the last century the isolation of pure lines was 

 practiced notably by the Englishman LeCoutour, who 

 isolated 150 varieties of wheat and by the Scotchman 

 Shirreff, who worked with various cereals. 



In recent years the principle has been extensively 

 applied with remarkable results, particularly by 



