AMT C24/2

In five cases the rosette was left handed but the capitulum right handed and in four the rosette right handed and the capitulum left handed; in one case both were right handed. Thus in nine out of fifteen cases the rosette and capitulum where in opposite directions.

b) Beneath the thirteen bracts enclosing the capitulum there are no other distinguishable structures.

It is suggested that the development of the daisy proceeds essentially as follows. First the petiole grows up from the rosette without any differentiation either of a visible anatomical form of an invisible chemical form. Subsequently the distal end of the petiole undergoes two kinds of change. Its diameter increases and at the same time a chemical pattern begins to form. The wavelength of this pattern is determined by purely chemical considerations, and there is therefore little reason to expect the wavelength to change much. As the diameter increases further therefore the pattern will have to change in order that it may continue to fit on the petiole with its new diameter. A very rough description of this process may be described as follows: