FURTHER STUDIES OF ELONGATION AND EXPANSION IN HELIANTHUS PHYTOMETERS

The investigation of the factors and functions involved in elonigation and expansion ulnder reduced light intenisity has been conitiniued with the special purpose of relating these to structural modifications as well as to growth forms. The ultimate objectives in these studies are to measure in terms of adaptation the climates and edaphic habitats characteristic of the various transplant gardens and to permit interpreting the functional responses of natives not susceptible of phytometer treatment. At the same time, opportunity was takeni to increase the number of light values to six, in order to simulate the whole range of natural habitats, as well as the control conditions in the lath-houses. In additioni, an inquiry was made into the effect of size of container, and a battery of free plhytometers was installed in the soil under each light intensity in order to integrate all the direct factors of the six eces.