38 HEREDITY 



plex organisms ; that is, in all organisms that are 

 apt to vary uselessly in a great number of ways. 

 Now animals are more complex than plants, and 

 therefore have a greater need for regressive varia- 

 tions. Hence it is that, while plants are not infre- 

 quently self-fertilised, animals, save in a very few 

 lowly cases, are not. He concludes his remarkable 

 chapter by saying that bi-parental reproduction 

 plays exactly the same part in selecting regressive 

 variations that natural selection plays in selecting 

 progressive variations. Bi-parental reproduction, in- 

 deed, is only another name for bi-parental selection. 

 It is almost as important a fact in evolution as 

 natural selection; though we must remember that 

 it is to natural selection that the evolution of sex 

 must ultimately be referred. 



It will now be desirable to pass from the methods 

 recounted in this chapter, methods mainly of actual 

 observation by the microscope or other means, to a 

 totally different point of view. Thereafter, perhaps, 

 we shall be able to see that some conclusions at any 

 rate are to be reached by widely diverse methods; 

 and this will constitute a high presumption in their 

 favour. Only after the reading of the next chapter 

 can we safely proceed to the more difficult and 

 important part of our subject. 



