20 THE MENDEL JOURNAL 



trace of his notes on this subject has so far been 

 discovered. The only other paper published giving 

 results of work on heredity was a little one on 

 Hieracium hybrids (" Ueber einige aus kiinstlicher 

 Befiuchtung gewonnene Hieraciumbastarde "), read in 

 1868 and published in 1869. Considering the great 

 amount of unfinished work which he must have had on 

 hand in 1868 it must ever be a matter for regret by all 

 biologists that Mendel became charged with adminis- 

 trative responsibilities which practically ended his 

 career as a scientific investigator. 



4. The Special Features of Mendel's Method of 

 WORK ON Heredity. 



Coming now to a closer consideration of Mendel's 

 work on the crossing of different races of plants, 

 we have first of all to notice that Mendel introduced 

 into the plan of his experiments three ideas which 

 have proved the most powerful means of research in 

 heredity that have ever been brought forward. 

 All three are very simple ideas and appear almost 

 self-evident necessities of any experimental work 

 on heredity, but they seem to have been quite novel 

 in Mendel's day, and I believe it is very largely 

 due to a want of a proper appreciation of these three 

 leading features of the Mendelian method of investi- 

 gation that so many wholly incorrect notions have 

 been, and, unfortunately, are still being disseminated 

 about Mendelism and even about heredity in general. 



The first idea is that of fixing the attention in each 

 experiment upon a single pair, or at most upon a few 



