Cross-Breeding and Hybridizing of IV heat. 71 



of cattle and other' species of animals, a discussion 

 will be presented giving expression to some of the facts 

 of variation by means of graphic illustrations, curved 

 lines and other diagrams. For the present it will be 

 sufficient to discuss the fact that greater variation is 

 produced, and the methods of ferreting out plants 

 which have the highest breeding power. The fact 

 should be at all times kept in mind that increasing, 

 variation of hybridization does not always increase the 

 average value of all the progeny. The practical busi- 

 ness fact is that it does increase the value of those few 

 which vary in the desired direction. By proper statis- 

 tical methods of breeding we simply throw out all but 

 the few best and base the new variety on these few. 

 We deal not with the average of a given hybrid, but 

 with the blood of the few best breeding individuals in 

 the hybrid. That hybridization causes variation is 

 shown by the photograph in Fig. 6. At the right in 

 the upper row of heads is the blue stem plant used for 

 the male parent, and at the left the fife wheat plant 

 used as the female parent. The middle and lower rows 

 represent types chosen from among the progeny, show- 

 ing that great variation was produced Here are 

 plants which resemble the female parent, others re- 

 sembling the male parent, and other plants which 

 resemble numerous other known varieties of wheat, 

 still others of entirely new types, compounded out of 

 the blood of the two parents. 



Henry Vilmorin, the great plant breeder and seeds- 

 man of Paris, showed the writer varieties of wheat 

 representing all of the sub-species of that grain which 

 he claimed to have produced by crossing two common 

 varieties of different sub-species. In some cases of 

 superior mother plants among hybrids there is no essen- 

 tial-variation in the botanical type, but in size of heads, 

 yield of grain per plant, quality of grain and other 

 individual characteristics, there may still be a difference 

 of a practical nature. There is also a very great 

 difference between the breeding power of these hybrid 



