290 REPRODUCTION 



attention has been devoted to experimental work upon the 

 character of hybrids, or crosses between varieties of plants, and 

 those exhibited by their offspring. 



Some remarkable facts were observed by Gregor Johann 

 Mendel in Germany about 1866, but the published accounts of 

 his work and the ' laws of inheritance ' deduced from it were lost 

 sight of until about 1900, when De Vries in Holland, Correns 

 in Germany, and Tschemak in Austria rediscovered similar facts. 



Mendel worked chiefly with garden peas, and crossed certain 

 varieties which differed from each other in regard to some 

 simple character or pair of characters. 



Among other experiments he crossed a variety of pea having 

 smooth round seeds with one bearing wrinkled indented seeds, 

 and found that the offspring consisted invariably of plants which 

 bore only smooth round seeds : the wrinkled character of the 

 parent crossed was not seen in the hybrid obtained. 



That character of the parent which appeared in the offspring 

 of the first cross he termed dominant, the character not seen 

 being spoken of as recessive. 



Seeds arising from the self-fertilisation of the flowers of the 

 round-seeded hybrid gave rise not only to round-seeded peas 

 but to plants with wrinkled seeds as well. 



The number of seeds showing the dominant round character 

 was found to be three times as many as those exhibiting the 

 recessive wrinkled character. 



Mendel continued the raising of plants from these seeds 

 through several generations, and found that the wrinkled seeds 

 bred true : they were as pure in respect of the recessive 

 character as the original parent, and never gave rise to round 

 peas. 



The round seeds, however, behaved differently. One in every 

 three bred true ; it was pure in regard to the dominant character, 

 but two of the round seeds in every three gave offspring which 



