HYBRIDISM 47 



eminently sensitive to changed conditions of life, fails 

 under these circumstances to perform its proper function 

 of producing offspring closely similar in all respects to 

 the parent-form. Now hybrids in the first generation are 

 descended from species (excluding those long-cultivated) 

 which have not had their reproductive systems in any 

 way affected, and they are not variable; but hybrids 

 themselves have their reproductive systems seriously 

 affected, and their descendants are highly variable. 



But to return to our comparison of mongrels and 

 hybrids: Gartner states that mongrels are more liable 

 than hybrids to revert to either parent-form; but this, 

 if it be true, is certainly only a difference in degree. 

 Moreover, Gartner expressly states that hybrids from long 

 cultivated plants are more subject to reversion than hy- 

 brids from species in their natural state; and this prob- 

 ably explains the singular difference in the results arrived 

 at by different observers: thus Max Wichura doubts 

 whether hybrids ever revert to their parent-forms, and 

 he experimented on uncultivated species of willows; while 

 Naudin, on the other hand, insists in the strongest terms 

 on the almost universal tendency to reversion in hybrids, 

 and he experimented chiefly on cultivated plants. Gart- 

 ner further states that when any two species, although 

 most closely allied to each other, are crossed with a third 

 species, the hybrids are widely different from each other; 

 whereas if two very distinct varieties of one species are 

 crossed with another species, the hybrids do not differ 

 much. But this conclusion, as far as I can make out, 

 is founded on a single experiment; and seems directly 

 opposed to the results of several experiments made by 

 Kolreuter. 



