5 o HIDDEN BEAUTIES OF NATURE 



In Great Britain and Ireland we can hardly 

 realize the power of this luminosity, as it is never 

 at its best around our coasts ; but in the Gulf of 

 Mexico the effect is splendid. 



Writers who have spent a great deal of time at 

 sea agree in saying that the light emitted by 

 marine forms of life is at times so powerful as to 

 permit books to be read with facility, and even to 

 illuminate the sails of the vessels. Not unfrequently, 

 on capturing specimens, they found the chief agent 

 to be a creature, about four inches in length and an 

 inch and a half in circumference, known as pyrosoma. 

 It is tube-shaped. When several of them were 

 taken up in a supply of sea water they withheld 

 their light, but when the water was shaken all 

 became brilliantly illuminated. The surface of the 

 pyrosoma appears to be studded with brilliants. 

 On other occasions the creatures that emitted the 

 light were microscopic noctilucae, while medusae play 

 a prominent part in this kind of illumination in all 

 seas and oceans. 



That the jelly-fishes emit light in a very marked 

 degree will be evident from the experiences of 

 Prof. A. Agassiz, related in the Voyage of the Blake : 

 ' As we lift our net from the water, heavy rills of 

 molten metal seem to flow down its sides and collect 

 in a glowing mass at the bottom. The jelly-fishes, 

 sparkling and brilliant in the sunshine, have a still 

 lovelier light of their own at night. They send 

 out a greenish golden light, as lustrous as that of 



