XVI 
GEOGRAPHICAL DISTRIBUTION OF PLANTS 
By Sm WiL.L1aAM THISELTON-DysErR, K.C.M.G., C.LE, So.D., F.RS. 
THE publication of The Origin of Species placed the study of 
Botanical Geography on an entirely new basis. It is only necessary 
to study the monumental Géographie Botanique raisonnée of 
Alphonse De Candolle, published four years earlier (1855), to realise 
how profound and far-reaching was the change. After a masterly 
and exhaustive discussion of all available data De Candolle in his 
final conclusions could only arrive at a deadlock. It is sufficient to 
quote a few sentences :— 
“L’opinion de Lamarck est aujourd’hui abandonnée par tous les 
naturalistes qui ont étudié sagement les modifications possibles des 
étres organisés.... 
“Kt si on s’écarte des exagérations de Lamarck, si ]’on suppose 
un premier type de chaque genre, de chaque famille tout au moins, 
on se trouve encore 4 l’égard de lorigine de ces types en présence de 
la grande question de la création. 
“Le seul parti & prendre est donc d’envisager les étres organisés 
comme existant depuis certaines époques, avec leurs qualités par- 
ticuliéres!.” 
Reviewing the position fourteen years afterwards, Bentham re- 
marked :—“These views, generally received by the great majority 
of naturalists at the time De Candolle wrote, and still maintained 
by a few, must, if adhered to, check all further enquiry into any 
connection of facts with causes,” and he added, “there is little doubt 
but that if De Candolle were to revise his work, he would follow the 
example of so many other eminent naturalists, and...insist that the 
present geographical distribution of plants was in most instances a 
derivative one, altered from a very different former distribution.” 
Writing to Asa Gray in 1856, Darwin gave a brief preliminary 
account of his ideas as to the origin of species, and said that 
* Vol. u. p. 1107. 2 Pres. Addr. (1869) Proc. Linn. Soc. 1868—69, p. lxviii. 
