STATISTICS OF METASPERMAE. 735 
or alone, is able to cast some additional light on the general 
problems of metaspermic history. Many other comparisons 
might be made and some of them would prove of definite value, 
but enough has already been brought forward to lay the found- 
ation of our understanding of the relations between the extra- 
continental element in its outside and inside ranging and in its 
connection with the general flora. 
The combination-ranges have not been worked out for the 
extra-continental element, but one or two facts are evident 
from the general survey of table E. For example the SE. 
range is particularly noticeable in the Manchurian-—Japanese 
element and the NEW. range, in the Siberian or European ele- 
ment. The SW. range is not unprevalent in the South Am- 
erican element. The wider extra-continental ranges are 
generally coérdinate with the wider intra-continental ranges, 
and vice versa. The explanationof the SE. preponderant-range 
of the Japanese-Manchurian element has been given as follows: 
The North American species which are found also in Japan, 
Manchuria and China were originally northwest in their Am- 
erican distribution. During the glacial period they were 
forced southeast along the lake-region trench of Canada and 
the boundary, thus reaching the Atlantic coast in the vicinity 
of New York or Delaware. Those which were pushed more 
directly south or west were destroyed through their inability 
to acclimate themselves at constantly higher altitudes. Only 
those which moved down the trench, and consequently south- 
east, were able to survive. The plants across Berings Straits 
were similarly induced to move southward into the unglaciated 
island of Japan, or into China and the Amur. There was 
thus brought about a division of the original northwest ele- 
ment in such a way that part of it became southeastern in 
North America and the rest eastern or north eastern in Asia. 
The relation between the Japanese-Manchurian region and the 
eastern North American is therefore to be explained from 
Tertiary and post-Tertiary wanderings, from glacial disper- 
sions and from topographical peculiarities of the two con- 
tinents concerned. All this has been ably discussed by Gray, 
Miquel, Nathorst, Saporta, Engler, Heer and others. 
A general table of range may now be presented; it is com- 
piled from Table D. and gives the number of species in each 
family that range north, east, south and west, and the total 
number of species in each family.- This table will serve as a 
termination of this line of statistical enquiry and following it 
the physiognomic elements will briefly be examined. 
