Abstract: Using nine varieties of wheat(Triticum)as female and two varieties of rye (Secale)as male, we made these crosses separately, and obtained hybrid plants from some crosses by embryo cultures.However, the F₁'s seeds were obtained only from the crosses of the two ryes with Stewart durum wheat(T. durum cv.Stewart). It is shown that natural doubling of chromosomes needs specifically genetic background(s).In Stewart×S. cereale the unreduced gametes were produced from pollen mother cells, and these F₁ hybrids were amphidiploids. The process of gametic production is similar to that of normal somatic division.Although the process of gametic formation was normal in Stewart×S.montanum, the numbers of chromosome of formed gametes were l～2l respectively. Thus, in the F₁'s seeds from this cross there were both amphidiploids and partial amphidiploids. Hence there are differences between Stewart×S. cereale and Stewart×S. montanum on the formation of amphidiploid.