THE GROWTH OF GROUPS 35 



> 

 intermediate forms. Moreover, these small gaps remind 



us strongly of those larger differences which may occa- 

 sionally be seen when comparing offspring and parent or 

 when examining a sport along with the putative parental 

 species. 



In concluding this introduction two points will be 

 emphasized. If it is true that our conception of a species 

 has changed it is necessary to modify our opinion as to 

 the origin of a species. Some of those who are interested 

 in the origin of species do not know how small are the 

 differential gaps which separate our modern species. 



