138 EVOLUTION 



converse. When from a single wild type 

 c mf*f*ml < rTn prorlTiTirigL n. nrmltiitiidfl of 

 we may speak of the result as 



a progress in differentiation: but we must 

 recognize that the term is only applicable 

 loosely, and that the obvious app^^r^nce of 

 increased complexity may in reality be the 

 f a process of simplification." 

 ilarly, "reversion occurs wiien the sum 

 :otal of the " 



_____ if! gfmiP^n'ffjflfl] typ^ " The T6- 



turn may be brought about by th^onmssion 



rij&xlsw^ 



Clement. Ii certain kinds of variation may 

 EeTcaHed " unpacking, '^reversion is re- 



In discussing the bearing of Mendelism on 

 the theory of evolution, Bateson makes three 

 important suggestions. (1) "One has only 

 to glance over trays of birds' skins, the port- 

 folios of a herbarium, or drawers of butter- 

 flies and moths, to discover abundant *jspecie&! 

 j^hich are analytical va.rifife. g ?f ^h^ " i.e. 

 differing jn the presence p? sfop?* ^ ^i^fi- 

 ilijgjactors. "TJie principles of heredity we 

 trace in our experimental breeding are operat- 

 ing throughout the natural world of species." 

 discontinuity in variatioi; 

 whether it be gal 



but hitkerto there has 



