Spiranthes Autumnalis. 197 



Of the three pistils, one is modified into a rostellum or 

 beak, r ; the other two are confluent, and form a cwp, the sur- 

 face of which is the stigma. This stigmatic surface, s, like all 

 other stigmas, becomes at a particular moment highly viscid, 

 attracting and retaining the pollen grains, which throw their 

 granular tubes down the loosened tissue, to fructify the ovules in 

 the ovary beneath, o. 



Six stamens, according to Lindley and Hooker, are dis- 

 coverable in the perfect orchis ; only one fertile anther is appa- 

 rent in Spiranthes, which now demands close attention. 



In examining a young Neottia with a pocket lens, and 

 looking into the flower, we observe two pale yellow spots in the 

 throat ; these are the pollen masses or pollinia lying under the 

 anther cell, a, and immediately over the stigma, s, attached to 

 the rostellum, r, by a boat-shaped disk, in such a position as 

 to render it highly improbable that the pollen grains of that 

 flower can ever touch their own stigma. If a needle is passed 

 into the flower, and this disk touched lightly, it will detach 

 itself, and with it the whole pollinia, as in fig. 5. 



This, on being pressed between thin glass under the 

 microscope, will show the square or oblong pollen grains 

 (fig. 6) ; or if applied to the stigmatic surface of an older flower, 

 these bright golden grains will adhere to the glistening green 

 cup, and be a beautiful object under a low power. 



Some flowers, if stripped of sepals and petals, as in fig. 4, 

 will show the anther cell empty, the stigma untouched, the 

 flower unfructified — where, then, is the pollinia ? 



This is Darwhr's discovery, that Spiranthes, like so many of 

 its brethren, is indebted to insect visitors for the perfecting of 

 its seed, depending also on the movement of its labellum, which 

 at one period closes the throat, and protects the young stigma 

 until its hour of maturity has arrived, then drops slowly down, 

 opening its honey glands to invite the wandering bee, which 

 bears upon its proboscis the pollinia previously extracted from 

 a younger flower. 



Resting on the sunny hills above Torquay, Darwin watched 

 the intercourse between insect and flower. The little Neottia 

 giving forth a sweet perfume to attract the living " winged 

 things ;" he saw the humble bee, as I have seen the hovering 

 Syrphidae and Tipulse, and small Hymenoptera enter the flower 

 cup ; but these only entered one flower, and then flew away, I 

 know not whither. Whereas he saw the bee always alight at 

 the bottom of the spike, and, climbing up regularly, withdraw 

 the pollinia from the upper and youngest flower, then fly to a 

 next plant, rest for a moment on the labellum, which is moved 

 aside, and whilst the insect sipped the nectar, the pollen mass 

 was received by the expectant stigma. Then again mounting 

 vol. n. — NO. III. p 



