470 MINNESOTA STATE HORTICULTURAL SOCIETY. 



AB and 25 per cent BB. It will always be found impossible 

 to fix the type AB, and these are called, "heterozygotes." This 

 word is from the Greek, meaning an ox and ass yoked to- 

 gether. AA and BB plants are the "homozygotes," being either 

 pure dominants, exhibiting the stronger characteristic only; 

 or pure recessive, exhibiting the weaker characteristic only. 

 Plants with dominant characteristics should be crossed to- 

 gether only; or the recessive plants only. Breed from the "homo- 

 zygotes," AA or BB, and not the "heterozygotes." This fixes the 

 type at once. 



Mendel's experiments, upon which the law was founded, were 

 conducted with garden peas, but wheat and many other plants have 

 since been tried. Some complex cases occur where the law appar- 

 ently does not fully apply, but it is confidently believed by various 

 workers on the problem in Europe that the law will apply in most 

 cases if not in all. It has been* found to apply equally as well to ani- 

 mals and has already been used efficiently in the breeding of poultry 

 by Professor Bateson of Cambridge University. Professor Bateson 

 was present at the conference and presented a paper on the "Practi- 

 cal Aspects of the New Discoveries in Heredity." 



The field of discussion opened up by Mendel's discovery is 

 so vast that the boundaries of the field are not yet apparent, but a 

 gateway has been made in what was formerly a black wall. It serves 

 to explain the "false hybrids" of Millardet,in which the character- 

 istics of one parent only are visible in the cross ; and the "mosaic 

 hybrids," in which the dominance of any one character is not appar- 

 ent throughout the plant but in part only of the different organs of 

 the same individual. It may be that the separation or segregation of 

 apparent characters sometimes occurs at other stages of growth 

 than that of formation of germ cells. If so then bud variations are 

 subject to Mendel's law. Under certain conditions a recessive char- 

 acter might be carried over a number of generations before crop- 

 ping out, which would explain atavism. 



The great importance of Mendel's discovery it is difficult to 

 overestimate. The whole question has been opened again, and with 

 the many workers in various parts of the world endeavoring to trace 

 the operation of the law it is confidently expected that much new 

 light will be thrown on the complex problems of heredity. Some 

 even think that we will be able to predict the outcome of any line 

 of crossing, that the work may be made synthetical as well as analy- 

 tical. There is an excellent field for demonstrating the limits of 

 Mendel's theory as applied to the breeding of hardy plants for the 

 Northwest. Plant-breeders now have a well-defined path blazed 



