200 
James Small. 
THE ORIGIN AND DEVELOPMENT OP THE 
COMPOSITE. 
By James Small, M.Sc. (Lond.), Ph.C. 
Chapter IX. 
FRUIT DISPERSAL IN THE COMPOSITE. 
A LTHOUGH there is a considerable variety of fruits in the 
family which are dispersed by animals, the chief dispersal 
mechanism is the pappus. The structure and evolution of this 
organ is dealt with in Chap. V. Its efficiency as a dispersal 
mechanism has been questioned by a number of observers and 
experimenters ; it was considered necessary, therefore, to investi¬ 
gate the problem experimentally, and the method and results are 
given in Section B of the present chapter, after the brief account 
of previous records in Section A. As the experimental results are 
somewhat at variance with accepted views the hydrodynamics of 
the simplest case are discussed in Section C. The bearing of the 
results on the problem of the development of the family is indicated 
in the last section of the chapter. 
A. History. 
The dispersal of seeds and fruits has been the subject of 
many observations. The literature of the subject was dealt with 
by Hildebrand (V, 32), and again by Hemsley (23). A further index 
of the literature from 1873 to 1890 is given by MacLeod (27), and a 
more recent bibliography by Sernander (33), who refers to Linne’s 
Ovatio de telluris habitabilis incremento of 1743 as the beginning 
of the study of plant dispersal. As there is a readily available 
account of the general phenomena with a good bibliography by 
Praeger (30) only special points will be mentioned. 
Cassini (8) was one of the first to consider fruit dispersal in 
the Compositse, and he differentiated eight methods by which the 
fruits are liberated from the capitulum. De Candolle (11) gave 
details of many species, and pointed out that many wide-spread 
species have no pappus. He formed the opinion that the pappus 
was effective as a means of dispersal for short distances only, i.e., 
up to half-a-mile. Hildebrand (V, 30) considered the various modi¬ 
fications in the fruit in relation to their dispersal, and gave 
examples from the Composite in his general treatise, and also in 
a previous account of hooked fruits (V, 31). Bentham gave a short 
