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POPULAR SCIENCE REVIEW. 
the Sensitive Plant, is not uncommon in the flower. An 
instance has been alluded to in the petals of the sundew ; it 
occurs also in the lip of the corolla of several of the orchis 
tribe. It is, however, more common in the proper organs of 
reproduction, as the style of Stylidium , the stamens of the 
berberry, &c., and is then directly connected with the process 
of fertilisation of the ovule. In Stylidium , an Australian 
genus, the style and filaments are adherent into a column, 
which hangs over on one side of the flower. When touched, 
it rises up and springs over to the opposite side, at the same 
time opening its anthers and scattering the pollen. The 
stamens of the various species of Berberis and Mnhonia , to 
the former of which our common berberry belongs, exhibit 
this irritability to a remarkable degree. If touched with a pin 
or other object at the base of the inside face of the filament, 
the stamen will spring violently forward from its place within 
the petal, so as to bring the anther into contact with the stigma, 
as shown in fig. 4, and will after a time slowly resume its 
original position. At first sight it may seem as if this con- 
trivance were intended to ensure the fertilisation of the pistil 
from the pollen of its own flower. In reality, however, the 
reverse is the case ; the excitation takes place in nature when 
an insect entering the flower for the sake of the honey in the 
glands at the base of the pistil, touches the inside of one of 
the stamens. The pollen is thus thrown on to the head or 
body of the insect, which carries it away to the next flower it 
visits, and leaves some of it on the stigma, and thus cross- 
fertilisation instead of self-fertilisation is secured. Similar 
motion of the stamens towards the pistil, but spontaneous, 
takes place in the case of the London Pride, and other species 
of Saxifraga. 
Elasticity is, indeed, a common property of organised tissue, 
though it is not often developed to so evident an extent. In 
the “ touch-me-not,” or Impatiens , we have a familiar instance 
in the seed-vessel, which, if touched when nearly ripe, suddenly 
coils back, throwing the seeds to a considerable distance. The 
“ squirting cucumber ” ( Momordica Elaterium) marks the 
period of ripeness by the fruit separating from its stalk, and 
expelling the. seeds and juice with great violence. Mr. Thomas 
Meehan described a remarkable instance of elasticity at a recent 
meeting of the Academy of Natural Sciences of Philadelphia. 
The seeds — or, as would appear from his description, more 
correctly the embryos of the seeds — of the American 66 witch- 
hazel ” ( Hamamelis virginica) are thrown out with such force 
as to strike people violently in the face who pass through the 
woods. Collecting a number of the capsules, and laying them 
on the floor, he found the seeds or embryos were thrown out 
