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luminosity ceases ; motion being resumed, light also re- 
appears. 
To me these observations, which are very easy of repetition, 
served as a starting-point for further inquiries. Phospho- 
rescence being so palpably associated with locomotion, it was 
only natural to seek the seat of the former in the muscular 
system. This I long essayed in vain. The employment of the 
microscope became necessaiy, and the difficulty lay in these 
circumstances. It was needful in the first place to adjust the 
instrument, so that the luminosity should be exhibited exactly 
at the focus ; and, secondly, that the light produced should be 
sufficiently powerful to be perceptible, notwithstanding the 
subdued light requisite to reveal the parts placed under the 
object-lens. After much groping, and many fruitless attempts, 
I succeeded in surmounting these difficulties ; and even whilst 
I write, it is a source of lively pleasure to me to recall the sense 
of astonishment with which I witnessed for the first time in 
a httle Polynoe (no doubt as brilliant an example as that which 
Ehrenberg has designated “ fulgurans”), the motor muscles of 
the bristles suddenly illumined before my eyes, under a mag- 
nifying power of 100 diameters. 
The muscles alone emitted hght, the other portions of the 
foot remaining perfectly obscure. 
But now another phenomenon presented itself quite unex- 
pectedly. What the simple lens had done in regard to the entire 
body, the microscope performed for the foot. These muscles again 
were not uniformly luminous throughout them entire length ; 
but there appeared disseminated over them a vast number of 
exceedingly minute, but at the same time remarkably brilliant 
points, which appeared and vanished again with the rapidity of 
lightning. 
The outhne which they presented consisted not of an unin- 
terrupted track of hght, but of a line formed by a succession of 
scintillations.* Lastly, I discovered that these scintillations 
(and consequently the “ phosphorescence ” which was visible to 
the eye) were only emitted diming the contraction of the 
muscles. An examination of the Syllidae and Ophiuridae re- 
vealed precisely the same phenomena as I had observed in 
Polynoe, and I therefore regard them as a confirmation of my 
views on this interesting subject. How is it possible that a 
luminosity manifested in the very recesses of the living organ- 
* The author compares the effect visible in this case to that exhibited by 
what he terms the “ magic tablet” of electricians. It is a tablet of glass on 
which representations are made with spangles of tin-foil, and when the dis- 
charge takes place, the figure appears in sparks of light, not in a continued 
luminous outline. A similar effect is produced in “ Barker’s spotted tube.” — 
See Jabez Hogg’s “ Elements of Natural Philosophy,” p. 450. 
