8G 



THE BOTANICAL MAGAZINE. 



[Vol. XXX. N.).351. 



a black (or blue) seeded strain and a white seeded strain which 

 we also met with among our maize materials. In the 

 tessellated graphical representation commonly used, i^2-Z3'gotes 

 will be distributed, to use the old formulae, as in the first of 



the two annexed digrams, where A denotes 

 the dominant black and a the recessive 

 white. Among these four Z3'gotes represented 

 in squares, we see from these factorial com- 

 positions, only two kinds of blue z\-gotes, AA 

 and Aa. 



But according to the new formula F.f 

 Z3'gotes will be as in the second diagram. 

 Each female gametic factor is represented twice, 

 so that the zj'gotes are all of triplicated com- 

 positions. Here we have thi-ee kinds of blue 

 zygotes 3i4, 2/1, a, A.2a all four zygotes being 

 thus different from each other. In both diagrams, the symbol 

 A may be taken for the intensit\'-unit of the blue colour, so 

 that the number of As, in each z3'gotic formula will represent 

 the intensity of the blue colour of the seed. The new factorial 

 composition is indeed more in accordance with the facts 

 observed, when we remember that it is a well known fact that 

 in maize the gradation of the intensity of seed colour is often 

 far more complex than may be expected. 



In the old construction, we have in the case of raonohybrid, 

 among four Z3'gotic fomulae three factorially different ones, 

 with dihybrid 9 different zj'gotic formulae among 16, with 

 trihvbrid 27 different ones among 64< ; while in the new con- 

 struction here proposed, zygotic formulae are all different from 

 each other. Thus among the zygotes formed, those correspond- 

 ing to different formula? will present different intensities of seed 

 colour, and we could distinguish them in practice when the 

 intensit}' unit is not too large or too small. 



CoRRFNS,'^ after having spoken of the triploid nature of 

 endosperm tissue of maize as above referred to, was to con- 



1) CoRRESS, C, rJl2, I.e. p. G(). 



