262 Small . — Irritability of the Pollen-presentation 
eyeglass. The following precautions must be noted for successful 
observations : 
(1) Irritability is shown only under good conditions of heat, light, 
and dryness. The movement is most active before 3 p.m. On cold or 
wet days species which show marked irritability under the proper con- 
ditions show very little or no movement. 
(2) Irritability is frequently shown only after the anther tube has 
opened and before the style is exserted, but there are many exceptions to 
this rule, especially in the Cichorieae. 
(3) Although several species continue to show irritability after the 
flowers have been removed from the plant, in most cases movement ceases 
after this treatment. 
(4) The anther tube should be touched gently . 
(5) The observation of the ‘ A ’ type of movement requires careful 
and sometimes prolonged examination of numerous florets before it can 
be recorded without doubt or considered absent altogether. 
(6) Species which show ‘ C ’ under the best conditions may show 
‘ B * or * A ’ under less favourable conditions. 
(7) Species here recorded as ‘ A ’ or ‘ B ’ may be found to show ‘ C ’ 
on examination in more favourable circumstances. 
The list gives the name of species, place where observed for the 
first time, and type of irritability, with remarks on the degree of irritability. 
Many of the observations have been confirmed by colleagues, by students, 
or by the writer on different occasions. Altogether 233 species and varie- 
ties have been examined, and this investigation has yielded 149 records of 
irritability, mostly new. To facilitate reference an ‘ x * has been placed 
opposite all British, introduced, or commonly cultivated species. In 
column 2 of the list K.R.B.G. = Royal Botanic Gardens, Kew ; E.R.B.G. = 
Royal Botanic Garden, Edinburgh ; C.U.B.G. = Cambridge University 
Botanic Garden ; C.P.G, = Chelsea Physic Garden ; A.C.G. = Armstrong 
College Garden ; F. = in the field. The numbers in brackets in the fourth 
column refer to the notes at the end of the list. 
Genus and Species, 
Place of 
Observation. 
T TyP e °f Reworks. 
Irritability. 
Achillea alpina, L. 
K.R.B.G. 
C 
slight 
Achillea Clavennae, L. 
E.R.B.G. 
C 
slight 
Achillea crustata, Schur. 
E.R.B.G. 
A 
marked 
Achillea grandiflora, Bieb. 
K.R.B.G. 
C 
very marked 
Achillea holosericea, Sibth. and Sm. 
E.R.B.G. 
A 
slight 
Achillea magna, L. 
K.R.B.G. 
C 
distinct 
X Achillea millefolium, L. 
F. 
C 
distinct (16) 
X Achillea Ptarmica, L. 
F. 
C 
distinct (16) 
Amellus annuus, Willd. 
K.R.B.G. 
C 
slight 
