74 
James Small. 
If the Senecio type of duplex hair be taken as primitive, it is 
clear that it has passed through several forms of reduction along 
the various lines of evolution suggested in Fig. 7, Chap. II, the 
elaters disappearing more or less in the Inuloid, Helianthoid and 
Asteroid lines, the hairs becoming reduced to single elater cells in 
the Mutisieae or to short external cells in the Anthemideae and, 
perhaps, passing below the epidermis in the Cichoriese. It is 
doubtful, however, whether the endocarpal filaments in the 
Cichorieae and Cynareae are homologous with the elaters. 
Development. —Before Buchenau published the first complete 
account of the development of the floret in 1854 (8a), Duchartre 
(16) had recorded some observations on Helianthus, from which he 
concluded that the two paleae on the top of the cypsela were 
epicalyx leaves or bracteoles, fused with the ovary for part of their 
length ; the calyx he considered to be completely fused with the lower 
part of the corolla tube. Duchartre also regarded the pappus in 
Bidens and all paleaceous pappi to be of a similar epicalycine 
nature. 
In subsequent observations apart from the phyllome or tri- 
chome nature of the pappus, the chief point recorded is the origin 
of that structure after the corolla and stamens have been dif¬ 
ferentiated, see Chap. IV, Sect. A, and the literature there cited. 
An isolated but interesting observation is that by Baart de la 
Faille (2), who, as an example of his thesis that logarithmic 
distribution is more frequent in nature than the normal curve, 
takes the top cells of the pappus in Senecio vulgaris, and shows 
that any increase in length is directly proportional to the length 
already acquired. 
Phyllome v. Trichome. — The question of whether the pappus 
in the Composite is a modified calyx-limb or merely hairs or 
emergences on the top of the so-called calyx tube is still a question 
of controversy, the latest contributions dating from 1916. 
The controversy reached its height about 1873, but Richard 
(58) had previously stated that the pappus had been recognised for 
a long time as analogous to the calyx of other families. He adds as 
a caution “ ndanmoins ce seroit une grande erreur d’assimiler en 
tous points l’aigrette aux calices ordinaires.” Cassini (11, Tome I, 
p. 202) describes the pappus as “ un ctdice epigyne, d’une nature 
particulifcre ” and analogises it (op. cit., p. 219) with the paleae of 
the receptacle and with the involucral bracts. His argument is 
“ ces paillettes et ces ecailles sont incontestablement des bractees. 
