Manchester Memoirs, Vo/. /vi. {igii-12). 3 



in the first hybrid generation (/i). If the matter is 

 followed further, however, by pollinating the flower of the 

 hybrid with its own pollen, then in the second hybrid 

 generation (/2), though the majority of the offspring 

 show the dominant character, a certain smaller proportion 

 show a reversion to the recessive form. Working with a 

 very large number of plants, Mendel was able to show 

 that the numerical ratio of dominants and rccessives in 

 the second hybrid generation was practically as 3:1. 



This simple numerical ratio was found by Mendel to 

 apply not only to these particular characters of roundness 

 and wrinkledness, but equally to all unit characters when 

 treated singly, and the numerous investigators who have 

 continued Mendel's experiments in a great variety of 

 plants and animals have in almost every case obtained 

 the same numerical results. The deduction drawn from 

 this simple numerical ratio is also in complete agreement 

 with what is known of the development of the reproductive 

 cells in both the vegetable and animal kingdom. Accord- 

 ing to Mendel's interpretation of his results, the first 

 hybrid generation, while displaying only the dominant, 

 yet contains in a latent form the recessive character, 

 and these two characters become segregated in the repro- 

 ductive cells of the plant, so that each egg cell and each 

 pollen grain possesses only one of them. From self- 

 fertilisation of the hybrid, therefore, four possible com- 

 binations might result. The egg cell bearing the dominant 

 character D might be fertilised by pollen bearing the 

 dominant character (d) or by pollen bearing the recessive 

 character (r). The egg cell bearing the recessive character 

 (R) might be pollinated by either form of pollen {<i or r). 

 The four resultant individuals would therefore be repre- 

 sented by the letters : 



Dd, Vr, Rd, Rr. 



