THE PHYSOGRADE ORDER. 



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shorter and much more slender fibres, which are coiled 

 up in spirals when the 

 main filament contracts, 

 and gradually spread out 

 as it lengthens. These 

 are very similar to the 

 small hooked threads at- 

 tached at intervals along 

 a fishing-line. TheBeroe 

 may be kept alive for 

 some time in a large 

 vessel of sea-water, but 

 it soon languishes, and 

 melts away to nothing. 

 A third order of Jelly- 

 fishes is called Physo- 

 grade. In these the body 

 is buoyed up by a sort 

 of bladder, which the 

 creature is said to have 

 the power of inflating at 

 will, so as to be able to 

 rise or sink at its plea- 

 sure. The best known 

 of this group is the Phy- 

 salia, or Portuguese man- 

 of-war, common in the 

 seas of warm countries, 

 but very rarely captured 

 on the British coasts. Oc- 

 casionally it is met with on the southern shores of 



