194 Prof. Gray on the Botany of Japan, 
duced, but the fact that they are remarkable goes to confirm the 
proposition. Indeed, the general expectation of botanists in this 
regard sufficiently indicates the common, implicit opinion. 
discovery of a new Sarracenia or a new Halesia in the Atlantic 
United States, or of a new Eschscholtzia, Platystemon, or Calais 
west of the Rocky Mountains, would excite no surprise. A con- 
verse discovery, or the detection of any of these genera in a 
remote region, would excite great surprise. The discovery of 
numerous closely related species thus divided between two widely 
separated districts might not, in the present state of our knowl- 
ge, suggest former continuity, migration, or interchange; but 
that of identical species peculiar to the two inevitably would. 
Why should it? Evidently because the natural supposition 
is that individuals of the same kind are descendants from a com- 
) 
and conscientious investigator formerly adopted and strenuously 
maintained Schouw’s hypothesis of the double or multiple origia 
of species, But in his great work, the Géographie Botanique Hat 
sonnée, published in the year 1855, he has in effect discarded 1t, 
and thi om any theoretical objections to that view, but be- 
cause he found it no longer needed to account for the general 
facts of distribution. This appears from his qualified, though 
dubious, adherence to the hypothesis of a double origin, a8 4 
ier ressort, in the few and extraordinary cases which he could 
hardly explain in any other way. His decisive instance, indeed, 
is the o Eastern American Phryma leptostachy4 
in the Himalaya Mountains. 
OR on are; or, in other Kye 
in species (1 rimordial 
“tind that derivative forma when segregated 
