on the Light emitted from various Bodies. 169 



till the 27th, but no light was emitted. What was the cause of 

 this failure in these two last experiments ? Was it the ten days' 

 increased growth of the animal, which was taken from the 

 same pond, that made the difference ? 



Exper. 13. The above experiments were repeated, when the 

 tadpole had just put on the state of a frog, but without produ- 

 cing any lucid appearance. 



The Light is incorporated with the whole Substance of Marine 



Fishes. 



Exper. 14. A fine fresh herring, being gutted, was divided 

 longitudinally into two parts, both of which were hung up, by 

 pieces of string, in the laboratory. On the 2d night, they were 

 very lucid on the skinny side, but not on the fleshy or inward 

 part ; on the 3d, the fleshy or central parts of the fish, were 

 thickly covered with a rich azure light ; on the 4th, they con- 

 tinued exceedingly luminous ; and on the 5th and 6th they 

 were still lucid. It is surprising to think what a profusion of 

 light was emitted from the interior substance of this single fish. 



Exper. 15. A similar experiment was made with a mackerel, 

 and with similar effects. These two experiments were frequentty 

 repeated. 



Exper. 16. But the soft-roe, of both the herring and the 

 mackerel, abounds more with light than even the flesh. When 

 it is in its most luminous state, which generally happens about 

 the 3d or 4th night, it will sometimes shine so very splendidly, 

 as to appear like a complete body of light. It is remarkable 

 that the hard-roe, in general, does not emit so much light as 

 the soft-roe. When the roes were used, they were laid upon 

 plates, and deposited in the laboratory. 



MDCCC Z 



