88 THOUGHTS ON ANIMALCULES. 



other animal structures ; for example, in the Meduscs *, 

 many of which are of considerable bulk, some a yard 

 in diameter, and several pounds in weight, yet, after 

 death, their entire structure rapidly melts away, and 

 the only solid residuum is a thin film of membrane, 

 weighing but a few grains. The Physalia, so famihar 

 to voyagers by the common name of " Portuguese Man- 

 of-war f," and which skims along the surface of the sea 

 at pleasure, using its little crest as a sail, and often ap- 

 pearing in mimic fleets of thousands on the cahn expanse 

 of the ocean, consists only of an oblong bladder wrinkled 

 into a crest above, and sending off numerous attenuated 

 filaments from below. When taken out of the water, 

 it shrinks into a shapeless mass of jelly, and all its 

 substance evaporates, leaving a portion of earthy mat- 

 ter, relatively as inconsiderable as the residual dust of 

 the innumerable hosts of the Infusoria. Thus, in the 

 Medusas, as in the animalcules, all the functions of 



* The Medusm are those elegant hyaline cup -shaped gelatinous ani- 

 mals, commonly known by the name of JeUy-fish, or Sea-blubber ; and 

 which, in the warm days of summer, may often be seen swarming in 

 thousands in the sea near our coasts, as at Southampton, Portsmouth, 

 &c. If one as large as a saucer is caught in the hand, and taken out of 

 the water, it instantly collapses into a small mass of jelly. '' A Medusa 

 weighing two pounds when first taken out of the sea, dried up to only 

 thirty grains of solid matter." — Professor Owen. 



f Physalia pelagica ; see Vignette of title-page. 



