Origin and Development of the Compositce. 255 
mechanical action of the keel and style in some Papilionatae. Juel, 
after a preliminary account, (27), extended the observations (28) to 
the Astereae, Helenieae, Senecioneae, Arctotideae, and Mutisieae in 
addition to the Inuleae, Heliantheae, Anthemideae, Cynareae and 
Cichorieae previously noted. The writer, after two preliminary 
notes (47-48), extended the list of *• irritables ” to 149 species and 
varieties (49), including the Calenduleae and ten other tribes pre¬ 
viously noted, but excluding the Vernonieae and Eupatorieae. Of 
the species observed 64% showed irritability. 
Another type of movement is described by various authors, 
namely a gradual and automatic contraction of the anther tube. 
This is mentioned (25) and figured (26) by Jacquin for Calea 
aspera. Jacquin, however,considers the inclusion of the anthers to be 
due to an elongation of the corolla, and this is shown in his figure. 
Cassini (6) considered the inclusion to be due to the withering of 
the stamens, but Brown (4) described it as “a vital action,and not 
the effect of withering or decay, which, however, speedily follows 
it,” and considered it to be analogous to the “ more evident 
motion .... in certain Cinarocephalae.” Another explanation was 
given by Meehan (41), who suggested that the filaments of Helianthus 
were stretched during exsertion by the growth of the style against 
the closed, upper end of the anther tube, and that the subsequent 
retraction was due, not to irritability, but to the elasticity and 
spontaneous contraction of the filaments. Asa Gray (13-14) 
controverted this, and gave experiments proving that the style 
does not stretch the filaments, and that there is a lateral movement 
through 15 or 20 minutes of an arc when two adjacent filaments 
are touched, much as in the Cynareas. Evans (11) has a note on a 
so-called unusual case of the re-exsertion of the style after the 
usual retraction of the style and stamens, but this is more or less 
usual, a typical case being Arctotis aspera as described by the 
writer (47, Fig. 1), who also found irritability of the ordinary type 
in a number of the Heliantheae, the tribe of which this slow retrac¬ 
tion of the anther tube is described as typical by Brown. 
This movement, however, occurs in most tribes, and it seems 
probable that a confusion has occurred between the ordinary type of 
irritability and the retraction of the stamens due to the loss of 
turgor in the filaments which immediately precedes the withering 
of these slender structures. Thus Cassini was right if this loss of 
turgor is considered the first step in withering, Brown was right 
if the process of dying is considered to be a vital process, Meehan 
