186 TREE ANCESTORS 



prisingly like the modem gum. There are species from Japan 

 on the east and from southwestern Asiatic Russia on the west. 

 The European records are innumerable and widely distributed 

 and the American records include Oregon and Colorado. If the 

 reader will turn to the accompanying plate the resemblance of 

 these ancient flowers, fruits and leaves to those of today will be 

 at once apparent. These figures are taken for the most part 

 from the wealth of remains preserved in the tiny Miocene Lake of 

 Oeningen on the Swiss border of Baden, and the leaves show the 

 same variation of three, four, five, or more lobed forms such as 

 can be matched today in any Southern swamp. 



The Miocene was followed by the Phocene and the gums were 

 stiU cosmopolitan in the Northern Hemisphere so that it is easy to 

 see why their distribution is what we find it to be at the present 

 time. Pliocene giuns have been found at very many localities 

 throughout central and southern Europe as well as on our Atlantic 

 coast, I have reproduced a worn gum ball collected from the 

 Pliocene deposits along the Main River in Germany on the accom- 

 panying plate, and the fruits found in the late Pliocene of Holland 

 are indistinguishable from those of the existing species of Asia 

 Minor. 



The Pliocene was followed by the Pleistocene or Glacial time and 

 the gums found fossil in this comparatively recent geological period 

 include traces of the existing Formosa and south China species, 

 which then still flourished in Japan, and the abundant leaves and 

 fruits of the existing red gum which have been found in West Vir- 

 ginia, North Carolina and Alabama. A leaf and fruit from the 

 Pleistocene swamp deposits along the Neuse River in North Caro- 

 lina are shown on the plate. 



That the gums which were so abundant throughout Europe in 

 the late Tertiary should have been entirely exterminated by the 

 glacial conditions while they survived in North America and Asia 

 seems strange but is readily understood when it is recalled that 

 high mountains and seas from the Pyrenees to the Caucasus made 

 it impossible for the gums to escape southward to more genial 

 climes and to return to the northward again when the cold stages 



