$6 James Small. 
while the inner bracts and the calyx limb are much reduced. The 
corolla is yellow in colour and zygomorphic. The stamens have 
the usual syngenesious anthers unequally appendaged. The ovary 
is bilocular with numerous ovules on axile placentae. 
As the years pass the species spreads (cp. Age and Area, Chap. 
X, A) until it reaches the zone, about 5000 ft. up on the slopes of 
the Andes, where the forest gives way to open scrub and grassland. 
Under the influence of the unfavourable conditions, (dryness, high 
winds, alternation of extreme temperatures,) the individual plants 
which become established in this region are stunted in growth and 
instead of scrambling over bushes become dwarf, trailing shrubs. 
In this form the species extends to higher altitudes where true 
alpines grow among the dwarfed, shrubby forms of species which 
are characteristic of the lower zone (cp. X, 69, Vol. II, p. 264). 
Under the more arid conditions the individuals which become 
established there are still more dwarfed. Coincident with the 
dwarfing of the individual, the reduction of the food supply causes 
the flowers to be smaller, the pedicels to be shorter (cp. Lysipomia 
acaulis, X, 72, p. 198), and the inner bracts and free calyx segments 
to disappear completely. This reduction enables the pressure of 
orthogenesis (as represented possibly by the climatic conditions) to 
crowd the flowers still closer (cp. I, 81, p. 30 and Chap. IV, B) and 
the corolla as a consequence becomes actinomorphic. The stamens 
as a result of correlation cease to be unequally developed, the 
anther tube becomes erect, the tooth-like appendages become 
equally developed on all the anthers (cp. Lysipomia mnscoides). As a 
result of the reduced food-supply only a few ovules are developed 
near the base of the ovary and the septum aborts (cp. Rhizocephalum 
and Lysipomia). 
Continued existence under these unfavourable conditions of 
excessive insolation, alternating with intense cold and combined 
with growth on the arid, wind-swept mountain slopes, would pro¬ 
duce crowding of all parts of the plant to give a rosette or ericoid 
form (cp. alpine Senecio Jacobea, Chap. X, A, also IX, 32, pp. 704— 
716 and X, 72, numerous figures). These epharmonic variations 
would include the complete disappearance of the pedicels, the 
formation of a properly protective, uniseriate pericline, an indefinite 
calyculus, and a head of small flowers (cp. the close aggregation 
of the capitula and formation of secondary involucres in alpine 
Composites), and also the development of only one ovule in each 
indehiscent ovary for the further protection of the seed. The 
