224 SOME NOTES ON THE VICTORIA REGIA. 



medium size ; and the third, a tier of one hundred and ninety or 

 more, small, tertiary tentacles, placed in groups of six between the 

 secondary ones. The stomach is long and tubular, extending 

 below the disc, and may be likened to the stick of an umbrella. 

 The mode of progression through the water is by the sudden con- 

 traction of the marginal ring, exactly like the rapid closing and 

 opening of an umbrella or parasol, and the individual appears 

 capable of directing its movements in whatever direction it 

 pleases." 



These jelly-fish have been sent to various places, with the view 

 of establishing it in other quarters, though we are afraid the deed 

 will be futile, as they have never been known to reproduce 

 themselves. Professor Lankester, in a letter to the writer, 

 states that the jelly-fish are produced by a little polyp, which 

 multiplies and creeps on the rootlets of NyniphceacecE and Po?ite- 

 deria. At certain times the polyp nip off a round piece from their 

 free extremity, which becomes a jelly-fish and grows and enlarges 

 to the adult size whilst floating in the water. 



The Rontgen Rays and Precious Stones. — The observa- 

 tions made by Bugust and Gascard on the possibility of distin- 

 guishing diamonds and jets from many of their imitations by the 

 application of the .v rays have caused them to make further 

 experiments. The transparency of aluminium to the rays has 

 since led them to study the effects produced in the case of precious 

 stones, of which that metal is a constituent. They find that the 

 crystalline forms of alumina known as corundum, ruby, sapphire, 

 emerald, topaz, and cat's-eye, may be classed between their imita- 

 tions and the diamond with regard to the effect produced. The 

 torquoise, which consists of aluminium phosphate, is also clearly 

 distinguished from its substitutes by means of the rays, and mallite 

 is almost as transparent as carbon. Fine pearls of small size are 

 less opaque to the rays than false ones of the same size, and may 

 be clearly distinguished from them ; but in the case of larger 

 specimens the result is less certain, depending greatly upon the 

 manner in which the false pearls have been made. — Pharm.Journ. 



