Mendel 's Principles of Heredity 541 



MENDEL'S PRINCIPLES OF HEREDITY. 



(Communicated by W. Ruskin Butterjield, Esq., of the Hastings 

 Museum.) 



The researches in plant-hybridisation of Gregor Mendel, an 

 Austrian monk, have conferred greatly increased importance 

 upon the practical study of heredity. Mendel's discoveries 

 were published in 1866 and 1870 ; but they escaped attention 

 until 1900, when Correns, Tschermak and De Vries indepen- 

 dently announced similar conclusions to those arrived at by 

 the previous investigator. 



It is well known that certain allied races of cultivated plants 

 and domesticated animals freely interbreed, and that their 

 offspring are mutually fertile. Now, if a plant or an animal 

 bearing a certain character be mated with another plant or 

 animal bearing a different character, it is sometimes found 

 that all the offspring exhibit one character to the exclusion 

 of the other. For instance, if a long-haired rabbit or guinea- 

 pig be crossed with a short-haired individual the litters are 

 always short-haired ; 1 similarly, if peas bearing violet flowers 

 be ciossed with peas bearing white flowers, the resulting 

 plants will bear violet flowers only. Mendel called the 

 character that appears a dominant character and the one 

 that is obscured a recessive character. 



But characters are not necessarily dominant or recessive. 

 In some cases one character is intensified ; thus, when a 

 variety of beans producing brown seeds is crossed with a 

 second variety producing white seeds, the hybrids produce 

 seeds a deeper brown than those of the brown-seeded parent. 

 Again, the offspring of buff pigeons by white pigeons are slate- 

 coloured, like the rock-dove, thus differing from both parents. 



Reverting to the hybrids in the first case mentioned — 



1 We have reason to believe that these results are not uniform. — Ed. 



