Origin and Development of the Composites. 257 
Arctotis aspera , L. 
The activities of the florets are best observed when the capitulum 
is examined on the plant in a green-house during warm, sunny 
weather. Anthesis begins about 8.30 a.m. in June; half an hour 
later the tips of some of the styles emerge from the anther tube 
and by 10 a.m. practically all the florets in the active whorl have 
their styles completely exserted; each style takes from five to ten 
minutes to emerge under the best conditions, and they are then 
sensitive to touch, bending from the base of the thickened portion 
towards the touch. The thickened portion is hairy and covered 
with pollen. When in a vigorous condition the style recovers its 
irritability in less than half a minute, but if touched so that it 
should react in an opposite direction from the previous movement 
two or three minutes rest are required in order to get a movement. 
This male stage of anthesis asts for only one day in the case of the 
outermost three rows of hermaphrodite florets. The florets nearer 
the centre are male, and in these the style acts only as a pollen 
presenter, and may be withdrawn and exserted again in an irritable 
condition for two or even three successive evenings and mornings. 
The styles in these florets are not re-exserted after the male stage, 
but those of the outer rows of florets are exserted in the female 
condition with the short style branches spread apart on the second 
day of anthesis and remain exserted until the conclusion of 
anthesis. As a rule only one row of styles is in the irritable phase 
each day at the beginning of the anthesis of the capitulum and two 
or three in the later stages; there is a diurnal progression of 
maturity towards the centre of the capitulum. 
Arctotis stoechadifolia, Berg. 
This species (syn. A. grandis) shows a similar series of events, 
but the stamens are also irritable, so that by touching the anther 
tube when the style is first exserted one can observe a movement in 
one direction, while if the style is touched on the opposite side 
it moves in the opposite direction, or the style may be stimulated 
first and then the anther tube. 
Gazania splendeus, X. 
This garden hybrid shows the same phenomenon as A. stoech • 
adifolia but much more markedly. If the anther tube is touched 
gently after anthesis has begun the style is exserted with striking 
rapidity, being fully exserted (to the extent of about half an inch) 
within two minutes in favourable conditions of light and heat. 
