LEOPOLD BUCH. 107 
I must first mention the great German geologist, Leopold 
Buch. Important observations as to the geographical dis- 
tribution of plants led him to the following remarkable 
assertion in his excellent “Physical Description of the 
Canary Islands” :— 
“The individuals of genera, on continents, spread and. 
widely diffuse themselves, and by the difference of localities,. 
nourishment, and soil, form varieties; and being in conse- 
quence of their isolation never crossed by other varieties, 
and so brought back to the main type, they in the end 
become a permanent and a distinct species. Then, perhaps, 
in other ways, they once more become associated with other 
descendants of the original form—which have likewise 
become new varieties—and both now appearas very distinct 
species, no longer mingling with one another. Not so om 
islands. Being commonly confined in narrow valleys or 
within the limit of small zones, individuals can reach one 
another and destroy every commencing production of a per- 
manent variety. Much in the same way the peculiarities or 
faults in language, originating with the head of some family, 
become, through the extension of the family, indigenous. 
throughout a whole district. If the district is separated and 
isolated, and if the language is not brought back to its. 
former purity by constant connection with that spoken in 
neighbouring districts, a dialect will be the result. If natural 
obstacles, forests, constitution, form of government, unite: 
the inhabitants of the separate district still more closely, 
and separate them still more completely from their neigh- 
bours, the dialect is fixed, and becomes a completely 
distinct language.” (Uebersicht der Flora auf den Canarien, 
S. 133.) 
