THE 
New Phytologist 
Vol. XVIII, No. 7. 
July, 1919. 
[Published September 10th, 1919.] 
THE ORIGIN AND DEVELOPMENT OF THE 
COMPOSITE.* 
By James Small, D.Sc., F.L.S. 
Chapter XIII. 
GENERAL CONCLUSIONS. 
HE results of the present investigation of the Composite 
are chiefly of two kinds; the phylesis of the family and 
of its chief groups has been elucidated, and various theories 
have been given to account for the origin and development of the 
structures and physiological and cytological phenomena which 
occur in the family. The historical evolution of the tribes is 
discussed briefly in the first chapter, together with previous 
phylogenetic suggestions. As these suggestions were in most cases 
based upon only one or a few characters it is unnecessary to 
discuss them in detail. It will be sufficient to point out that the 
affinities of the tribes suggested in the present account have 
almost all been recognised by previous synantherologists. 
The results of general importance are summarised below. 
Styles and Stamens. The evolution and biological significance 
of the appendages of the styles and stamens have been elucidated 
and the general economy-tendency has been shown to extend to 
the polliniferous tissue. The two general principles, “ the pro¬ 
gressive sterilisation of potentially sporogenous tissue ” and the 
elaboration of the sterilised tissue, are exemplified in the evolution 
of the anther appendages. 
Irritability of the Stamens. Our knowledge of thigmotropism 
of the stamens has been extended to all the tribes, except the 
Eupatorieae and Vernonieae, and to most of the sub-tribes of the 
family. Subsidiary results of the investigation of irritability are 
the new record of thigmotropism in the style of Gazania splendens t 
the differentiation of five types of movement of the stamens, and 
the theory of the differential changes in the permeability of the 
cells of the filaments as the cause of the movement. 
* Part of a Thesis approved for the Degree of Doctor of Science in the 
University of London. 
