2 Weiss, Researches on Heredity m Plants. 



number of plant hybrids, and the investigations, however 

 careful, were confined to a consideration of the first hybrid 

 generation. 



It was not until the spring of 1900 that three experi- 

 menters — De Vries, Correns and Tschermack — drew 

 attention to the important work of the abbot Mendel, 

 published in 1865, on the laws of inheritance in hybrids, 

 which, though referred to by Focke in his Pflajtzenbastar- 

 dierung, had remained unappreciated for half a century, 

 probably owing to its having been published in a periodical 

 of very limited circulation. 



In the same way the important experiments made by 

 Naudin about the same time (1856-1862), and the laws 

 he deduced from his experiments, have received little 

 notice until quite recently, when Blaringhem has drawn 

 attention to the work of this investigator, and has re- 

 published the generalisations, which are in striking agree- 

 ment with some of those of Mendel. 



Mendel's experiments were carried on partly with 

 different races or strains of cultivated plants (peas), partly 

 with various species of hawk-weeds. In the former case 

 he pollinated varieties of the common pea with pollen of 

 varieties differing from the maternal plant in one or more 

 characters. One of the distinctive features of Mendel's 

 work was the recognition of these unit characters and 

 their behaviour in the first and subsequent hybrid genera- 

 tions. One of the simplest instances of the independence 

 of unit character is seen in the easily repeated experiment 

 of Mendel, in which he pollinated the flowers of a variety 

 of the common pea characterised by its round seeds with 

 the pollen of a variety bearing wrinkled seeds. The 

 resulting hybrid produced round seeds, so that of the two 

 allelomorphic characters, as they have been termed, round- 

 ness of seeds is dominant, while wrinkledness is recessive 



