18 JOUENAL OF THE EOYAL HORTICULTURAL SOCIETY. 



From each of these trials there could then result only the following 

 forms : — 



1. AB, ABb, AaB, AaBb. 



2. AaBb, Aab, aBb, ab. 



3. AB, ABb, AaB, AaBb. 



4. AaBb, Aab, aBb, ab. 



If, furthermore, the several forms of the egg and pollen cells of the 

 hybrids were produced on an average in equal numbers, then in each 

 trial the said four combinations should stand in the same numerical 

 relation. A perfect agreement in the numerical relations was, however, 

 not to be expected, since in each fertilisation, even in normal cases, some 

 egg cells remain undeveloped or subsequently die, and many even of the 

 well-formed seeds fail to germinate when sown. The above assumption 

 is also limited in so far that, while it demands the formation of an equal 

 number of the various sorts of egg and pollen cells, it does not require 

 that this should apply to each separate hybrid with mathematical 

 exactness. 



The first and second trials had pre-eminently the object of proving the 

 composition of the hybrid egg cells, while the third and fourth trials 

 were to decide that of the pollen cells. As is shown by the above 

 demonstration the first and second trials and the third and fourth trials 

 should produce precisely the same combinations, and even in the second 

 year the result should be partially visible in the form and colour of the 

 artificially fertilised seed. In the first and third trials the dominant 

 characters of form and colour, A and B, appear in each union, and are 

 also partly constant and partly in hybrid union with the recessive 

 characters a and b, for which reason they must impress their peculiarity 

 upon the whole of the seeds. All seeds should therefore appear round 

 and yellow, if the theory be justified. In the second and fourth trials, on 

 the other hand, one union is hybrid in form and in colour, and conse- 

 quently the seeds are round and yellow ; another is hybrid in form, 

 but constant in the recessive character of colour, whence the seeds are 

 round and green ; the third is constant in the recessive character of 

 form but hybrid in colour, consequently the seeds are angular and yellow ; 

 the fourth is constant in both recessive characters, so that the seeds are 

 angular and green. In both these trials there were consequently four sorts 

 of seed to be expected — viz. round and yellow, round and green, angular 

 and yellow, angular and green. 



The crop fulfilled these expectations perfectly. There were obtained 

 in the 



1st Trial, 98 exclusively round yellow seeds ; 

 3rd ,, 94 ,j ,, 



In the 2nd Trial, 31 round and yellow, 26 round and green, 27 angular 

 and yellow, 26 angular and green seeds. 



In the 4th Trial, 24 round and yellow, 25 round and green, 22 angular 

 and yellow, 27 angular and green seeds. 



A favourable result could now scarcely be doubted ; the next genera- 

 tion must afford the final proof. From the seed sown there resulted for the 



