of Development of Vegetation on the Earth. 
161 
plants sucli as oak and pine mingled with palms and other tropical 
plants and witli extra-European Sequoias, Cinnamons, Dryandras, etc. 
Having worked out an explanation of tkis stränge mingling on the 
supposition tliat tliese were assemblages of plants brougbt togetlier 
which bad grown at different elevations, Ettingshausen was led to 
abandon tbat theory by a visit to the fossils in situ at Steiermark, 
and became at once convinced tbat the Coniferce, Uetulacece and 
Ctipuliferee bad not lived in zones above the Palms and Jfusacea, but 
tbat the otkerwise enigmatical association of tbese plants is easily 
explained by supposing tbat the predecessors of our European 
species, wkick differ front tbeir descendants in many respects, were 
able to exist in a warmer climate. 
In comparing the Tertiary Flora with tbat now living, Ettings- 
hausen considers the former as a collective stock-flora, wbicb may 
be analysed into its component Flora-elements. By Flora-elements 
be means all those ancient. plant-forms wbose representatives at 
present belong exclusively to, and characterize some natural floral 
region. 
The genetic relationsbip of some of the forest trees of the American 
Continent, for example, to Tertiary trees can be traced directly front 
horizon to borizon, as in the case of Castanea atavia to C. vesca. 
In the development of our European Flora the analogues of trees 
now living in America have played tlie most important parts. In 
the Tertiary times the Vegetation of the whole earth is supposed by 
Ettingshausen to have bad one and the sante character, distinguisked 
by the general mixture of wliat he terms all the Flora-elements — as 
far at all events as climatic conditions allowed, — which contained 
w ithin itself the elements frotn which all existing Floras are 
derived . 1 
He characterizes these Flora-elements as ckief-elements , 2 and col- 
lateral-elements . 3 For example, the Mid-European Flora-element 
in the Tertiaries Stands in reference to the existing Flora of Europe 
as chief-element ; whilst all the exotic forms contained in the same 
beds stand in the relationsbip of collateral-elements. "We frequently 
see certain plants taking their place in the natural Flora of a region 
which appear extraneous to the general character of tliat Flora, sorne- 
times even so abundantly represented as to influence the character 
of the Flora. These are descendants of collateral-elements. 
Beference is then made to the Flora of Japan, which presents a 
mixed assemblage of tree-forms, recalling forcibly the Flora of our 
Tertiaries. In tbat place are to be seen growing side by side 
apparent representatives of the Vegetation of the East Indies and the 
Amazons, of Europe and North America. 
The same mingling of types is seen, tkougli less markedlv, in the 
woods of North America. The Southern States possess endemic and 
European, Japanese and sub-tropical forms. In neitker case could 
this be the result of immigration. 
1 The Flora of America, it may be remarked, is now known to have heen at least as 
distinet from tliat of Europe in Cretaceous (?) times as at present. — J. S. G. 
2 Haupt-element. 3 Neben-element. 
DECABE II. — YOL. IV. — XO. IV. 
11 
