120 



LOCK : STUDIES IN PLANT BRHKI >l N < : 



3.— A non-black torm crossed with Pollen from the Heterozygotes. 



Kx-pt. 40. — (Yellow dent x White dent) x (White dent x 



Black Mxican.) 



Table 15. 



Total 1,788 



3,643 



5.431 



32 9 



67 I 



The comparatively wide variation in the percentage of 

 black grains on individual plants in the case of the last series 

 (3) must depend upon differences in the seed parents which 

 we have no means of checking. 



Considering now the above results 1,2. and 3 ( Expts. 38, 

 39, and 40) : in series 1 , if Mendel's law holds good, we must 

 suppose that — in terms of percentages of the whole — 25 white 

 grains are of the nature w x w, and 25 black grains are of the 

 nature b x b. Among the remaining 50 grains, which we 

 suppose to be of the nature w x b or b x w, 32-27 were 

 actually found to be black. This number agrees closely with 

 these obtained in the case of series 2 and 3. We must, there- 

 fore, suppose that in 1 also a nearly equal number of black 

 grains arises from each of the reciprocal methods of fertili- 

 zation w / b and b x w. 



I orrene i cplained a similar numerical resull in the ease of a 



sell fertilized heterozygote, bj supposing thai in this generation (as 



known to be th< n F,) b X w gave blue exclusively, whilst 



uch a percentage of blue ae bo make up the remaining 



number actually found* The results obtained in series 2 and •'{ above 



m to preclude such a p — ibilitj in the present instant e 



