90 





OX ALL ORGANIC BEINGS C hai>. XV. 



be exactly intermediate between that of the two 

 parent-breeds. With respect to the very slight differences 



>r even of 



cv 



Inch the individuals of the same sub-variety 

 allied varieties, are characterised, it is obvious that free c 

 Mould soon obliterate such small distinctions. The for 

 of new varieties, independently of selection, would also thus be 

 prevented ; except when the same variation continually recurred 

 from the action of some strongly predisposing cause. Hence we 

 may conclude that free crossing has in all cases played an im- 

 portant part in giving to all the members of the same domestic 

 race, and of the same natural species, uniformity of character 

 though largely modified by natural selection and by the direct 

 action of the surrounding conditions. 



On the possibility of all organic beings occasionally intercrossing. 

 •But it may be asked, can free crossing occur with herma- 

 phrodite animals and plants ? All the higher animals, and the 

 few insects which have been domesticated, have separated sexes, 

 and must inevitably unite for each birth. With respect to the 

 crossing of hermaphrodites, the subject is too large for the pre- 

 sent volume, and will be more properly treated in a succeeding 

 work. In my ' Origin of Species,' however, I have given a 

 short abstract of the reasons which induce me to believe that 



11 organic beings occasionally cross, though perhaps in some 

 cases only at long intervals of time. 13 I will here just recall 

 the fact that many plants, though hermaphrodite in structure, 



re unisexual in function : —such as those called bv 0. K. 







Sprengel dichog amous , in which the pollen and stigma of th 



same flower are matured at different periods; or those called 

 by me reciprocally dimorphic, in which the flower's own pollen 

 is not fitted to fertilise its own stigma; or again, the many 

 kinds in which curious mechanical contrivances exist, effec- 

 tually preventing self-fertilisation. There are, however, man) 

 hermaphrodite plants which are not in any way specially cor 

 structed to favour intercrossing, but which nevertheless con 



T 



mingle almost as freely as animals with separated sexes. This 

 is the case with cabbages, radishes, and onions, as I know from 



13 With respect to plants, an admir- 1867) has lately been published by Dr. 

 ftble essay on this subject (Die Gesch- Ilildebrand, who arrives at the sanio 

 lechter-Verthcilung bei den Pilanzen: general conclusions as I have done. 







