124 ANIMAL AND VEGETABLE PHOSPHORI. 



to get near it ; so that though it was straight before, it will in time 

 become crooked, that it may get near the light. It is not the 

 heat, but the light of the sun, which it thus covets; for, though 

 a fire be kept in the room, capable of giving a much stronger heat 

 than the sun, the plant will turn away from the fire in order to 

 enjoy the sun's light. The green colour of plants also depends on 

 the sun's light being allowed to shine upon them : for without this 

 they are always white. 



With the various secretions, and even solid parts of many of 

 these substances, the matter of light unites most intimately ; in 

 other classes of animals and vegetables it exists more loosely, and 

 consequently is more easily separated from them. 



This separation appears to take place in two ways : first during 

 life, by a peculiar set of organs, which have a power of secreting 

 it from the general fluids of the rest of the body; and secondly, 

 by the tendency to decomposition, which uniformly takes place 

 upon death ; in consequence of which, agreeably to the universal 

 law of chemical affinity, homogeneous particles unite themselves 

 with homogeneous particles, and escape in a more sensible, be. 

 cause in a more aggregate and concentrated form. 



Upon this simple view of the subject we may easily account for 

 all the phenomena noticed by successive observers, and narrated 

 in the preceding part of this article, as well as for a variety of 

 others of a similar character. The light thus thrown forth was 

 till very lately regarded as phosphorescent, especially by Spallan. 

 rani and Fourcroy; while Caradin believed it to be innate, and 

 formed by some chemical process of the organs of the animal exhi. 

 biting it. That it is not of a phosphoric nature is clearly proved, 

 because it is in no instance, and in no respect inflammable; and 

 hence we have preferred to treat upon this subject under the pre. 

 gent title, rather than under that of phosphorescent substances, 

 the title generally selected by which to characterize them. But 

 whether it be not in some instances generated internally, instead 

 of being derived ab extra, is by no means equally well ascertained. 

 Many luminous animals appear to shun the. light of the day, and 

 seem scarcely to expose themselves sufficiently to its influence, to 

 be able to throw forth such a quantity as we see issue from their 

 bodies. Yet, on the. other hand, it should not be forgotten that 

 almost all substances whatever, mineral as well as animal and 

 vegetable, and gasseous and liquid as well as solid, absorb and 

 contain a great quantity of latent light, a part of which may enter 



