12 
THE PRINCIPLES OF BOTANY. 
be confounded with the so-called black bryony , which is the 
common Tamus, a very different plant, with entire shining 
leaves.” The white bryony is our only native species of this 
fine order, whose most conspicuous examples are mostly tro¬ 
pical, and such delicate plants as cucumbers, melons, gourds, 
pumpkins, &c., some of which may be transferred to open 
borders in summer, sufficiently attest to the variety and grace 
of the whole order. Besides a large variety of edible cu¬ 
cumbers, melons, &c., it yields two most powerful medicines, 
namely— 
1. Momordica elaterium, wild or squirting Cucumber . 
2. Cttrullijs ( Cucumis , Linn.). 
Colocynthis. — The bitter Cucumber , or Colocynth. The 
drug known as Elaterium is prepared from the wild cucumber, 
which, according to Pereira, gets the name now given to the 
medicine from eAarrjpiov (from IXavw, I impel or urge for¬ 
ward) ; the term was employed by the Greeks to signify not 
merely a medicine prepared from the glkvq aypiog, or wild 
cucumber ( Memordica elaterium ), but also any purgative 
substance. Whether or not it was first employed as a me¬ 
dicine upon the principle of signatures is uncertain, but it is 
highly probable that the peculiar squirting action of the fruit 
suggested its use; but be this as it may, the manner in which 
the seed is expelled from the fruit (called a pepo) is sufficiently 
interesting to deserve description. It would appear that when 
the fruit is ripe its seeds are expelled with a semi-fluid sub¬ 
stance from its interior with the force of water from a syringe, 
and hence the oame of squirting cucumber given to this wild 
species. Dr. Pereira describes this action as follows : 
“ The phenomenon of the expulsion of the seeds of this 
plant has acquired of late years increased interest from the 
circumstance of Detrochet having adduced it as one of the 
effects of endosmosis. It is well known that when two fluids 
of unequal density are separated from each other by mem¬ 
brane (animal or vegetable), a double permeation of fluids 
takes .place; that is, each fluid passes through the membrane 
and mixes with the other fluid; the current in one direction is 
called endosmosis , and that in the opposite direction exos¬ 
mosis, 
“ Now, to apply these facts to the phenomena of Elaterium 
apple. In the centre of this fruit and surrounding the seeds 
is a very singular variety of organic matter which appears 
like thick mucus. It is called by some botanists c placentary 
matter .’ External to this—that is, in the tissue of the peri¬ 
carp—there is another organic liquid, whose density is less 
than that of the placentary matter. These two fluids, being 
