PART III. | THE MECHANISMS OF FLOWERS. 173 
_asharp ridge (5, 6,2) which fits into a groove on the carina (4, 5, 2) ; 
_ (2),a sharp triangular tooth (4, 5, /) is borne by the carina behind 
\ this groove, and catches in the space (5, 6, h’) behind the ridge on 
_ the inner surface of the ala; and (3), the upper borders of the ale 
are folded inwards for a linet space (3, 5, 6, m’), and at this fold 
_ they cohere together above the carina. Close in front of the spot 
_ where the upper borders of the alse are thus firmly applied to each 
' other, the apex of the carina emerges when the alz are pressed down. 
| The upper margins of the carina are coherent except at the apex, 
' where they leave a longitudinal slit, and when the carina (along 
_ with the ale) is depressed, there emerges from this slit a ribbon- 
_ shaped mass of pollen, pressed forwards by the thickened ends of 
the ten stamens (8, 7). 
When the pressure is removed the ale and carina return to their 
i former position ; when they are again pressed down another portion 
_ of pollen is pressed out. After the greater part of the pollen has 
been squeezed out in this way, the stigma (8 s) emerges at the same 
_ slit; it has lain imbedded in pollen in the carina but emerges free 
= Ben it, for its papillze are not yet adhesive and the pollen-grains are 
scraped off by the edges of the slit. 
____ If the stigma is rubbed with slight pressure over a glass plate a 
line of moisture marks its course; if it be now brought in contact 
with pollen, the pollen adheres to it so firmly that it is not easily 
_ removed. Doubtless the same effect is produced by insect-visits ; 
1 he flower gives up pollen to the ventral hairs of its first visitors ; 
and after its pollen is spent, the superficial cells of the stigma 
coming in contact with the insect get ruptured and exude their 
fluid contents; pollen from other flowers, with which the insect is 
already dusted, now adheres to the stigma and the act of cross- 
fertilisation is complete. Whether in absence of insects the flower 
is fertilised by its own pollen has still to be decided by a simple ex- 
periment. I observed the following bees fertilising this plant near 
a (1) Bombus silvarum, L. § (10'), s.; (2) B. hortorum, L. 2 (21), s.; (3) 
i B. muscorum, F. ? (13—14), s. ; (4) Osmia aurulenta, Pz. 9 (8—9), ep., (all 
very frequent). I also saw Lycena alsus, W. V. 9, and a Capsus vainly 
\ ~ attempting to suck the honey. I have seen it visited on the Alps by 12 
| Bepecies of bees, and 10 of Lepidoptera (609). 
 —~Doryenium (Bonjeania) hirsutum, Ser—According to Delpino, 
_ the flower has a piston-action, and the ends of the filaments are 
: ‘ ickened (179, p. 45). 
: ‘ 1 These numbers in brackets indicate the length of the insect’s proboscis, 
