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was contained. Could there have been combustion in these 
two cases? Very accurate and searching experiments, it 
appears to us, would be requisite before a reply could be given 
in the affirmative. 
Lessou was one of the first, if not the first observer, who 
considered phosphorescence to be a distinct phenomenon, 
resulting from physico-chemical action, and bearing a direct 
relation to some vital act; but the expressions employed by 
him are far too vague to possess any practical value ; and, more- 
over, he is himself not satisfied with his opinions, and insists 
upon the necessity of special researches on the subject.* 
Macartney, Todd, and Coldstream, consider phosphorescence 
to be due to an imponderable agent, to nervous emanations 
modified or influenced by the action of certain organs. The 
last-named observer, judging by the luminous track left by the 
snail, imagines that phosphorus, or some similarly luminous 
substance, may enter into the composition of the fight-pro- 
ducing organs, f 
Meyen and Becquerel, although they admit various kinds of 
phosphorescence, do not explain the diversity of causes from 
which the phases of phosphorescence are derived. Ehrenberg, 
in his elaborate treatise on the subject, appears inclined to 
attribute all the varieties of phosphorescence emitted by 
animals to one sole cause. According to his views, it results 
from vital action, and is produced in a manner somewhat 
analogous to the electricity of certain fishes. He thinks that 
the luminous mucus is secreted in a passive state, and is called 
into action by luminous discharges. (?) So far the views of this 
eminent savant accord with some of the theories hitherto pro- 
pounded ; but he goes still further, and he has confirmed an im- 
portant fact, which was revealed to me before I became aware 
of the labours of Ehrenberg ; namely, that under the microscope 
a fight, which was before steady and uniform, is resolved into a 
vast number of minute scintillations. Ehrenberg, moreover, 
attributes the production of light, in most cases at least, to the 
influence of the reproductive organs. 
My own observations have revealed to me three different 
phases of phosphorescence, from which may be inferred actions 
of a totally distinct character, all resulting ultimately in the 
production of luminosity. 
1. I have witnessed in Pholades and Medusae , the secretion 
* Did. des Sciences Naturelles, art. “ Phosphorescence.” 
t Cyclopcedia of Anatomy and Physiology, art. “ Animal Luminousness.” 
Macartney and Todd think “ that the luminous organs concentrate and 
modify the nervous influence, so as to form it into light.” So that, according 
to this theory, annual luminousness is an effect solely of vital power ; and tills 
view is to a great extent confirmed by the experiments of Koelliker. — Ed. 
