4 
James Small. 
variation. The observations by Fovveraker (loc. cit.), Hauri (36), 
and Schroter and Hauri (60) furnish other examples of similar 
epharmonic variation in cushion-plants of widely different taxonomic 
affinities (cp. Schimper IX, 32, pp. 704-716). 
It is a significant fact that the first detailed studies of the 
peculiar insular floras both of New Zealand (15-17) and of the 
Sandwich Islands (51) have resulted in the emphasis of epharmonic 
variation. Bews (6-7) dealing with the many peculiar Composites 
of Natal seems to take the same view although he uses epharmony 
in Vesque’s sense, not in Cockayne’s (see below Chapter XI). He 
writes (7) of the study of epharmony as giving a deeper insight into 
the causal relationship of environment to plant form. 
One of the most extraordinary cases is the change observed in 
Cnicus ayvensis by Compton (18) who records that after a flood in 
the fens all herbaceous plants were killed except Cochlearia 
armoracia , the rootstocks of which sprouted after drainage, and a 
few specimens of Cnicus arvensis , which seemed normal but were 
attached to the soil by two to three feet of slender, leafless stem, 
exactly like the woodless stem of a true aquatic. Considering that 
the thistles probably owe their origin to the heat and dryness of the 
centre of origin (see below) this epharmonic adaptation in a few 
weeks to an aquatic habitat is very striking (cp. Warming on 
Polygonum nmphibium, 71, p. 371). 
Other cases are (a) woodiness in the stem of a marsh plant as 
the effect of water at 30-40° C (27), ( b ) various modifications similar 
to those of arctic plants as the effect of continuous or discontinuous 
electric illumination (8), (c) desiccation and excessive insolation as 
the cause of spines (48), ( d ) the alpine habit in Seneciojacobaea etc. 
induced by the alternation of low temperatures and darkness with 
high temperatures and strong insolation (9). 
There are also other experimental or observational papers by 
Oger (56), Harris (33), Dauphin^ (22), Constantin (19), Shreve (63- 
64), Bailey and Sinnott (5) and Jeffrey (43, Chap.XXX). 
Age and Area. The Age and Area Law which has been 
demonstrated by Willis (75-82) is the most important contribution to 
geographical botany since the Origin of Species. As the original 
accounts and various reviews (20,23-24,49,65,67) are easily accessible 
it will be sufficient to note that the formal expression of the law is 
that “ the geographical distribution of a species (i.e. the area which 
it includes within its outer localities) within a fairly uniform country 
not broken by serious barriers depends, so long as conditions remain 
constant, upon the age of that species within the country.” 
