“SEA-PENS.. T19 
The sea-pens are prickly. One species is striped with red, an- 
other is a dark grey; in the evening they become phosphorescent. 
Linnzeus tells us that the phosphorescent sea-pens which cover the 
ocean bottom cast so strong a light that it is easy to count the 
fishes and worms which sport around them. These polypiers 
often contract the lower part of their axis, and again distend it ; 
they have also the same power in their wings. The latter ap- 
pendages appear to act also as sails and oars; but the united 
effort of the polypes only produces a very imperfect movement. 
The waters carry them hither and thither, and the currents bear 
them on their course. Floating involuntarily, at the sport of the 
winds and waves, they are driven everywhere, and wherever they 
are, there they find that nourishment which is necessary for their 
sustenance and the reproduction of their species. 
According to the recent researches of M. Lacaze-Duthiers 
these polypes of the pennatula are either all male or all female ; 
so that all the members of each community are of one sex. There 
are vegetables organised on the same plan, that is to say, which 
have their male and female flowers on different stems—the Dates, 
for instance. 
