312 TlMEHRI. 
je£ts above the surface of the water, and which portion 
generally takes the form of an air-bladder transversely 
grooved, drawn out nearly to a point at both ends and 
with a strong crest or keel along the entire upper portion. 
From the under side of this float depends a very variable 
number of more or less tubular parts which together 
make up a colony comparable to a plant-like colony of 
Hydra-like polyps, but one in which the various indivi- 
duals have been modified to fulfil very different functions 
for the common good. Thus certain parts are feeding 
polyps, furnished with a mouth leading to a simple bag- 
like cavity or stomach ; others are more or less protective, 
and serve to cover over the feeding individuals ; while 
others again, which are extremely elongated, often 
several feet in length, and are abundantly provided with 
stinging cells, serve as grapnels and offensive and 
defensive weapons. It is these line-like tentacles alone 
which possess the disagreeable stinging properties so 
characteristic of the Portuguese man-of-war, a property 
due to the presence of minute cells provided with a coil 
of fleshy threads tipped with a poisonous barb, which, on 
contact of the body with any foreign substance, is violently 
darted out. As experience shows, and as the structure of 
the parts indicates, the float and the shorter depending 
parts may be handled with impunity, but the long 
grapnels may not be thus handled, since the attempt 
is accompanied by a most acute and long-lasting 
irritation and pain. Hidden in among all these parts 
will be found others which are concerned simply with 
the production of sexual elements for reproduction. 
By many writers it is stated that the air cavity of the 
float communicates with the atmosphere, and that thus 
