104 
POPULAR SCIENCE REVIEW. 
On the various Contrivances by which British and Foreign Orchids are 
Fertilized by Insects, c Oc. By Chas. Darwin, M.A. (Illustrated.) 
Murray. 
HE perusal of Mr. Darwin’s book on “ The various Contrivances by 
which British and Foreign Orchids are fertilized by Insects,” might 
incline the reader to regard it as the result of nothing less than a life de- 
voted exclusively to the subject. Yet of the great discussion concerning 
the “ origin of species,” the present work is, in fact, only a single chapter, 
the details of which have become inconveniently large to be incorporated 
with the rest of the argument. 
The point which the author here seeks to establish is thus stated. “ That 
nature abhors perpetual self-fertilization.” “ That marriage between near 
relations is in some way injurious — and that some unknown great good is 
derived from the union of individuals which have been kept distinct for 
many generations.” 
Self-fertilization is a rare event with the Orchids, and the description of 
the various contrivances by which the pollen of one plant is kept from 
contact with its own stigma and conveyed to that of another plant of the 
same species, occupies nearly the whole of the volume. 
Orchids, it appears, are favourite plants with honey-loving insects. 
When the proboscis of a bee or a moth is inserted into the nectary of an 
orchid, it first comes in contact with a little capsule or pouch, the mem- 
brane of which at the slightest touch is ruptured, setting free a liquid and 
exposing the sticky ends of two club-shaped organs, to the further ends of 
which the pollen grains are attached. The sticky ends instantly adhere to 
the proboscis, which, when retracted, carries with it the pollen clubs 
fastened upon it in a somewhat erect position. Further down the throat 
of the nectary lies the stigma. 
We have then to observe (first), the retired position of the anther 
chambers, of which there are two, containing the charged ends of the 
pollen clubs. (Second.) The prominent position of the viscid ends of the 
pollen-clubs in the throat of the nectary. (Third.) The manner in which 
the sticky ends of the pollen-clubs are kept moist, till wanted for use, by 
being immersed in a little pouch of liquid. (Fourth.) The extreme sen- 
sitiveness of the lips of this pouch, which open at the slightest touch 
imaginable. (Fifth.) The rapid setting of the viscid matter, which 
hardens into a dry cement in a very short time after the sticky ends of the 
pollen-clubs have touched the proboscis of an insect. (Sixth.) If the 
attached clubs remained erect, the proboscis at its next insertion into a 
flower would press the pollen grains into a position similar to that from 
which they had been taken, namely, into the anther chambers ; but no 
sooner are the clubs fast than their pedicels uniformly begin to curl for- 
ward, bringing the pollenized ends of the clubs almost close to the pro- 
boscis in a more forward position, so that when the next flower is visited 
the proboscis pushes the pollenized tips of the clubs past the anther chambers 
and right upon the stigma of the flower. 
In the genus Catasetum the flower has two slender horns, which when 
