200 



HA RD WICKE'S SCIENCE- G OS SI P. 



PHOTOGRAPHY BY VITAL PHOSPHOR- 

 ESCENCE. 



By Dr. John Vansantv 



SOME months ago there was published in several 

 scientific journals, an article showing how ex- 

 cellent photographic positive prints, on glass or 

 paper, could be made from an ordinary negative by 

 means of the transformed or " stored-up " radiant 

 energy — the phosphorescent luminosity — of certain 

 inorganic substances, especially particular sulphides 

 of calcium and strontium. 



Many organic substances also, as is well known, 

 possess this property of storing-up, so to speak, and 

 afterwards emitting, as more or less luminous rays, 

 the radiations to which they have been exposed. 

 Crystallised carbon, in form of the diamond, and 

 white paper may be cited as illustrations of this 

 class. A photographic latent image on a bromide 

 of silver surface, capable of being developed, 

 can easily be produced by bringing into contact, for 

 an hour or so, in the dark, such a sensitive surface, 

 and an engraving, or some ordinary printing on 

 white paper which has just been previously exposed 

 for some minutes to the direct rays of the sun. 



But I have now to call attention to the curious 

 act, that the kind of light given out by certain animal 

 organs, and which evidently in its causation has some 

 close relation to the nervous system and vitality of 

 the animal, and belongs to a different class of 

 phenomena from the phosphorescence above men- 

 tioned, can also bring about incipient decomposition 

 in a haloid salt and silver. Moreover, it can do this 

 through a sheet of glass of the usual thickness used 

 for photographic negatives, and, consequently, there 

 is a possibility of producing by such light photo- 

 graphic positive prints. 



The following experiment, copied from my notes, 

 proves this : 



June 8, 1887. This evening, just after dark, I 

 took about a dozen fire-fiies (Lampyris corusca), which 

 had been captured a fevf minutes before on the lawn, 

 and enclosed them in a wide-mouthed vial of some 

 3 oz. capacity, having a piece of fine white bobinet 

 (such as is used for ladies' veils) stretched over its 

 mouth in place of a stopper. Enclosed thus, they 

 would frequently emit the momentary flashes of 

 greenish-tinted yellow light for which they are re- 

 markable, though usually only one insect at the same 

 time would flash. Every few seconds one or 

 another would emit its light for a period which I 

 estimated to average in each case about one-half of a 

 second, and the frequency of the emissions could be 

 increased by gently shaking the vial. When not 

 flashing, the under surface of the three posterior 

 segments of the fire-fly's abdomen, from which 

 the light came, was scarcely at all luminous, but 

 was simply of a bright yellow colour. The flash- 



ing was plainly under control of the insect, like its 

 muscular movements. These fire-flies are rather less 

 than three-quarters of an inch long, and the segments 

 which become luminous have, altogether, an area of 

 only about one-eighth of an inch square. The flash 

 is, however, quite bright, so much so that fine print 

 can be easily seen when held close to it. 



Repairing to my dark closet with the vial of fire- 

 flies, I placed it to one side, under cover, whilst I 

 arranged and clamped a very sensitive gelatino- 

 bromide of silver dry plate beneath an ordinary 

 negative picture of a landscape on glass, as for 

 contact printing 



The vial of insects was then inverted over the back 

 of the negative, so that only the fine meshes of the 

 bobinet and the glass of the negative with its gelatine 

 film intervened between the fire-fly's light and the 

 sensitive bromide plate. I counted the flashes, 

 occasionally shaking the vial and sliding it over the 

 negative, till fifty flashes had occurred. 



The vial was then removed, the sensitive plate 

 separated from the negative, and an attempt made to 

 develop the latent image, if any existed. Alkaline 

 solution of pyrogalol was used, and, in a few minutes, 

 I had the pleasure of seeing a well-marked positive 

 image of the negative picture appear, the plate being 

 somewhat yellow stained, as if from too long an ex- 

 posure. This was fixed in the usual way with sod. 

 hyposulph., and is now in my possession, — probably 

 the first picture ever produced by the light emitted 

 from a living animal organism. 



U.S. Marine Hospital, St. Louis, Mo. 



NOTES ON CH^TOPTEKUS VALENCINII. 



IT 7HILE other branches of marine zoology have 

 V V received a full share of attention from both 

 Scientist and " Tyro," it is astonishing what little has 

 been given to the large and interesting class of 

 annelids ; apart, of course, from that of specialists, 

 with the results of their work wrapped up in " Trans- 

 actions." 



On one or two occasions only during the last five 

 years, as far as I can remember, have writers in 

 Science-Gossip favoured us with a few notes on 

 some of its members. 



In the endeavour to help in making up such defi- 

 ciency, I send the above sketch, and a few remarks 

 upon its subject. 



This is the Chcetopterus Valenciiiii of Quatrefages, 

 perhaps identical with the C. insignis of Baird, but 

 of this I am not certain, as I have found one or two 

 specimens of another species on this coast, too much 

 damaged, unfortunately, to make out much of their 

 structure. 



The one at present under notice is an animal 

 which, for grotesque appearance, will readily put 



