532 DEVELOPMENT OP THE N.O. MYRTACEjE % 



in that proportion, was there a tendency for those genera, which 

 were not endemic in Australia, to oust those which were peculiar 

 to Australia. This, again, suggested that the genera peculiar to 

 Australasia had developed amid rigorous and harsh conditions, 

 and had not yet accommodated themselves to a genial and ex- 

 tremely moist climate. 



To most of these rules, however, the genera Acacia and Eucalyp- 

 tus formed exceptions. Whether in harsh or genial surroundings, 

 in heat or cold, in soil either good, poor, rich or sandy, these genera 

 rarely failed to establish themselves firmly. Nevertheless, elastic 

 of temperament as they were, Acacia and Eucalyptus both 

 appeared to be ill-adapted to cope with the advance of those 

 genera not peculiar to Australia, when in an environment of abun- 

 dant shelter, good soil, and with heavy and continued precipita- 

 tion. This suggested the failure of even Acacia and Eucalyptus 

 to compete with the Indian and Antarctic floral elements, when the 

 latter were in their true environment. The range of habitat of 

 these genera, however, is highly instructive. Thus certain Euca- 

 lypts* with transverse leaf-venation, with a characteristic essential 

 oil known as pinene, and with peculiar anthers, flourished on the 

 poor sandy soils. Other Eucalypts, again, such as the Boxes, flour- 

 ished in heavy clay soils, and possessed much cineol or eucalyptol, 

 a characteristic leaf-venation, and, morever, they possessed peculiar 

 anthers opening in pores. Still a third group, embracing such 

 forms as the Peppermint and the Snow-Gums, possessed much 

 phellandrene oil, a parallel venation, and kidney-shaped anthers; 

 and they occupied the moister and cooler portions of the plateau- 

 regions. The Acacias were found in all soils indifferently, but 

 their morphology was found to be peculiar in proportion to their 

 adaptation to certain climatic and soil-surroundings. In the case 

 of the Eucalypt, this suggested an origin in open sandy country, 

 but an ability later, by the production of special devices, to flourish 

 on the heavy soils, and in cold, moist climates. 



* R. H. Cambage, Presidential Address. Journ. Proc. Roy. Soc. N. S. 

 Wales, 1913. 



