2 
James Small. 
(1825), while Lindley (I, 56)and Schultz Bipontinus (1, 77) treat of 
of the subject in a somewhat perfunctory manner. The last 
developed his preliminary remarks in a later contribution (61). 
Nees (1, 67) gives a table of the distribution throughout the world 
of the then (1833) known genera of the Heterochrominae. As 
illustrations of the new outlook on the problems of geographical 
distribution the papers by Andrews (3-4) and Capitaine (13) on the 
Leguminosae, by Himmelbauer (39) on the Berberidaceae and by 
Gates (28-29) on certain Liliaceae may be quoted. These accounts 
correlate all, or at least most, of what is known about the plants 
with their distribution, and sound views on the evolution of the 
groups are more likely to result from this method than from the 
older method of purely morphological comparisons. 
Land bridges in various parts of the world are brought in to 
solve many problems (cp. 74 and 82) and the Antarctic connection 
between Fuegia and New Zealand has been much written about (58, 
66, etc.), but Hutton (42) points out that such a bridge probably 
did not exist after the origin of the Angiosperms, except in the form 
of an archipelago. In the Compositae, as was indicated in Chapter 
IX, we must explain the distribution with the land surface of the 
world as it is to-day. 
Concentration at High Levels. The extreme abundance of the 
Compositae at high levels is noted in almost all alpine investigations ; 
it is mentioned by Cassini (I, 18,Tome 1, p. 324.), Spruce (69, p.288), 
Whymper (73, pp. 199 and 352) and Guppy (IX, 21, Vol. II, p.238) 
who quotes Hemsley (37), Hooker and Ball (40) and Schimper (IX, 
32) as authorities. Hemsley (37) quotes figures for concentrations 
along the mountains from the Caucasus to Japan and suggests the 
pappus mechanism as the cause. Ball (5a) gives 25-30% as the 
proportion of Composites in the higher Andean flora. 
The local dominance of Composites over other plants is well 
known from common experience with daisies, dandelions and thistles. 
Interesting cases of complete dominance are given by Darwin (21, 
p. 113), who mentions beds of the cardoon thistle ( Cynara card- 
unculus) “many (probably several hundred) square miles” in extent 
where “nothing else can now live”, and also by Geddes (30), who 
found the Great Ragweed ( Ambrosia trifida) covering a ravine with 
a dense growth of plants 12 to 18ft. high. 
Action of Environment. The direct effect of environment on 
the individual is rapidly becoming one of the most fertile fields in 
the domain of experimental evolution. Although the origin of new 
