Origin and Development of the Composites. 227 
initiated by Siegesbeckia, was carried further until all the disc florets 
were sterile; then the style branches remained permanently closed, 
since the style survived only as a pollen presenter, and Melampodium 
came into being about the time of the middle Oligocene. 
Meanwhile, further south, among the headwaters of the 
Amazons, Mutisia was being developed from Trixis by floral changes 
accompanying a recovery of the ancestral scandent habit as des¬ 
cribed above. The Mutisia type repeated the travels of its grand¬ 
parent Senecio and re-ascended the Andes, undergoing the changes 
necessary for existence on the more arid and windy mountain slopes. 
Food material for the capitulum being scarcer, the ray florets 
became reduced or sometimes ceased to be developed; the pappus 
regained its wind-dispersal function and was developed to a 
greater extent. In addition the scapigerous form was taken in the 
more barren regions where it was necessary. During this interest¬ 
ing journey Mutisia , in fact, became Onoseris. 
Having regained an efficient wind-dispersal mechanism, the 
Onoseris type spread quickly. By a few slight changes, including 
the abortion of the inner lip of the corolla in the outer row of florets, 
which was quite natural under the unfavourable conditions of the 
Andine habitat, Chaptalia was evolved. The pappus being retained 
in an efficient condition, the mountain path north along the 
Rockies, across the Alaska-Siberian bridge and south along the 
mountains of Asia, was open for Chaptalia. This migration took 
place in the upper Oligocene and on reaching the plains of China 
the genus suffered the natural changes on regaining a mesophytic 
habitat. Increased food supply led to a redevelopment of the 
aborted inner lip of the outer corollas and a reduction in the 
number of protective ealyculine leaves; Chaptalia in this way 
became Gerbera on crossing the Alaska-Siberian bridge. 
The end of the Oligocene saw the initiation of a number of 
subsidiary lines of evolution, the most important of which was 
again connected with important geological events. The Mediter¬ 
ranean end of the Central Sea was undergoing considerable 
shrinkage, and this led to the development of spines in the Inula 
group. At the same time mutational changes developed the fimbrillae 
of the receptacle into deeply lacerate alveoles, which surrounded the 
young fruits and to a certain extent prevented the pappus from 
exercising its normal function. The pappus setae, therefore, fused 
in various ways and the Buphthalminae originated. 
The shrinkage of the Central Sea continuing into the lower 
Miocene, a strongly insolated, semi-desert region was produced at 
