CHAPTER VI 



INHERITANCE ON CROSSING! MENDEL*S LAW 



IN 1865 Gregor Mendel, Abbot of Briinn, in Silesia, 

 published the results of his now famous experiments 

 in the crossing of common peas. His paper appeared 

 in the Proceedings of the Natural History Society of 

 Briinn, and it lay buried and forgotten in this publica- 

 tion for five-and-thirty years. Mendel lived before his 

 time, for apparently no one who knew of his paper 

 was capable of realising its importance. In 1900, after 

 the law which Mendel discovered had been simultane- 

 ously rediscovered by three separate investigators, the 

 original paper was brought to light. 



Many different men had carried out hybridisation 

 experiments previous to Mendel's time. The only 

 generalisations which were reached were that the first 

 cross between two varieties was usually more or less 

 intermediate in character, and usually very uniform ; 

 and that in the following generation there was much 

 variability, specimens being found which very nearly 

 resembled either of the original parents, along with 

 all kinds of intermediate types. 



The great advance which Mendel made was in that 

 he did not consider the plant as a whole, but studied 

 the behaviour of each individual character. Further, 

 he carried on his experiments systematically for several 

 generations, and carefully counted the numbers of the 

 different types which occurred. 



He selected the common culinary pea for several 

 reasons. It is prolific and easily grown. It is always 

 self-fertilised, hence there could be no opportunity for 

 promiscuous crossing, even when different varieties 

 were grown side by side. Further, there are many 



