Ill MENDEL'S WORK 27 



time and attention, but uhhappily the record of these 

 experiments appears to have been lost. The only other 

 published work that we possess deahng with heredity is a 

 brief paper on some crossing experiments with the hawk- 

 weeds (Hieracium) , a genus that he chose for "working 

 with because of the enormous number of forms under 

 which it naturally exists. By crossing together the more 

 distinct varieties, he evidently hoped to produce some of 

 these numerous wild forms, and so throw light upon their 

 origin and nature. In this hope he was disappointed. 

 Owing in part to the great technical difficulties attending 

 the cross fertihsation of these flowers he succeeded in ob- 

 taining very few hybrids. Moreover, the behaviour of 

 those which he did obtain was quite contrary to what he 

 had found in the peas. Instead of giving a variety of 

 forms in the F2 generation, they bred true and continued 

 to do so as long as they were kept under observation. 

 More recent research has shown that this is due to a pe- 

 culiar form of parthenogenesis (cf. p. 13^), and not to any 

 failure of the characters to separate clearly from one an- 

 other in the gametes. Mendel, however, could not have 

 known of this, and his inability to discover in Hieracium 

 any indication of the rule which he had foimd to hold 

 good for both peas and beans must have been a source 

 of considerable disappointment. Whether for this 

 reason, or owing to the utter neglect of his work by 

 the scientific world, Mendel gave up his experimental 



