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POPULAR SCIENCE REVIEW. 
rostellunij and bringing away one of the pollen-masses^ at- 
tached by its viscid disc^ as shown in fig. 6 a. 
Now, let ns suppose,^^ says Mr. Darwin, our insect to fly to 
another flower, or insert the pencil, with the attached poUinium, 
into the same or into another nectary, by looking at fig. 6 a, it 
will be evident that the firmly attached pollinium will be 
simply pushed against or into its old position, namely into its 
anther cell. How, then, can the flower be fertilized ? This is 
effected by a beautiful contrivance ; though the viscid surface 
remains immoveably affixed, the apparently insignificant and 
minute disc of membrane to which the caudicle adheres, is 
endowed with a remarkable power of contraction, which causes 
the pollinium to sweep through about ninety degrees, always in 
one direction, viz., towards the apex of the proboscis or pencil, 
in the course, on an average, of thirty seconds. The position 
of the pollinium after the movement is shown at h, fig. 6. 
Now, after this movement, and interval of time (which would 
allow the insect to fly to another flower), it will be seen that if 
the pencil be inserted into the nectary, the thick end of the 
pollinium will exactly strike the stigmatic surface."’^ 
Another beautiful adaption then comes into operation. It 
has been said that the stigma is viscid. As soon as the mass 
of pollen touches this viscid surface, some portion adheres, 
whilst the viscidity is not sufficient to pull away the whole 
pollinium from the head of the insect, so that it may fly from 
flower to flower, and fertilize several in succession, until all the 
pollen is exhausted. The structure of the pouch of the 
rostellum in which the discs of the pollinia are inserted, is also 
worthy of observation. When in their natural position the 
discs are kept moist by the fluid surrounding them' in this pouch; 
but when removed the discs dry rapidly, and lose their power 
of adhesion in a few minutes. So elastic is this pouch, that 
when depressed by the contact of a foreign object, it is bent 
forwards so that the pollinia are easily removed; but as soon as 
the pressure ceases, the pouch returns to its former position, 
and thereby economizes the moisture it contains, which would 
otherwise too speedily evaporate. As a whole, the mechanism 
by which this and many other orchids are fertilized, is so perfect 
and beautiful, that the account reads like a fairy tale, or rather, 
like a new Bridgewater Treatise, in which great theological 
truths are demonstrated without the aid of Theology. 
The next species which offers any considerable variation in 
structure from the Early Orchis, is the Pyramidal Orchis 
{Orchis pyramidalis) . In this species the stigmatic surfaces 
are two distinct rounded spots, one on each side of the rostellum. 
Then, again, the rostellum overhangs the entrance to the 
nectary. The pollinia are not separate, but both pollen-masses 
