Interface administrators, Administrators (Semantic MediaWiki), Curators (Semantic MediaWiki), Editors (Semantic MediaWiki), Suppressors, Administrators, trusted
17,043
edits
m
no edit summary
mNo edit summary |
mNo edit summary |
||
| Line 29: | Line 29: | ||
If, as Professor Huxley somewhere observes, the pathways of science are strewn with the murdered myths of antiquity, it is equally true that of late physiological inquiry has been instrumental in resuscitating many a previously-rejected superstition. From comparatively old times—for the nineteenth century—has descended the curiious supposition that the object last visible to the dying eye is imperishably photographed upon the dead retina. Most readers will recall to mind tales of retributive justice based upon the identification and conviction of a murderer through the agency of his photograph in a dead man’s eye; and at least once within the last ten years the plot of an acting drama, not to mention half a dozen sensation novels founded upon the same thesis, has been made to turn upon the terrible witness of such a rogues’ gallery. The fact—for it is the fact that such testimony is possible—has been authoritatively denied, over and over again, by physiologists of established reputation, sneered at as a relic of metaphysical speculation reinforced by morbid fancy, and finally scoffed down as among the utter impossibilities. But it turns out, as has often been the case before, that this grim conception of poetic justice was founded in fact, and that under certain circumstances the development of such ''in articulo mortis'' images, latent though they are, as identifiable photographs, is a very simple and practicable process. | If, as Professor Huxley somewhere observes, the pathways of science are strewn with the murdered myths of antiquity, it is equally true that of late physiological inquiry has been instrumental in resuscitating many a previously-rejected superstition. From comparatively old times—for the nineteenth century—has descended the curiious supposition that the object last visible to the dying eye is imperishably photographed upon the dead retina. Most readers will recall to mind tales of retributive justice based upon the identification and conviction of a murderer through the agency of his photograph in a dead man’s eye; and at least once within the last ten years the plot of an acting drama, not to mention half a dozen sensation novels founded upon the same thesis, has been made to turn upon the terrible witness of such a rogues’ gallery. The fact—for it is the fact that such testimony is possible—has been authoritatively denied, over and over again, by physiologists of established reputation, sneered at as a relic of metaphysical speculation reinforced by morbid fancy, and finally scoffed down as among the utter impossibilities. But it turns out, as has often been the case before, that this grim conception of poetic justice was founded in fact, and that under certain circumstances the development of such ''in articulo mortis'' images, latent though they are, as identifiable photographs, is a very simple and practicable process. | ||
<center>{{Style S-Small capitals| | <center>{{Style S-Small capitals|an obvios moral.}}</center> | ||
The moral is that whatever is beautiful has always, in some strange way, a capacity for rising from the dead, and contains within itself the germ of its own resurrection. Says a German mystic, from whom Mr. Emerson has caught the inspiration of more than one aphorism:—“Die Rose ist ohne Warme, sie bluhet weil sie bluhet,” typifying beauty, of course, under the symbol of that poetically hackneyed blossom. Plato, dreamiest of all dreamers, has the same fancy that Mr. Emerson has parodied from the German in | The moral is that whatever is beautiful has always, in some strange way, a capacity for rising from the dead, and contains within itself the germ of its own resurrection. Says a German mystic, from whom Mr. Emerson has caught the inspiration of more than one aphorism:—“Die Rose ist ohne Warme, sie bluhet weil sie bluhet,” typifying beauty, of course, under the symbol of that poetically hackneyed blossom. Plato, dreamiest of all dreamers, has the same fancy that Mr. Emerson has parodied from the German in | ||
| Line 41: | Line 41: | ||
The regeneration of this old myth is in its way an example of that longevity of all things beautiful, that may well point a moral to such scientific Alcibiades as have dared to speculate whether poetry can co-exist with science. When, as in this instance, a deeper science constantly verifies what a shallow science has denied—the eternity of the beautiful because it is beautiful—one need not trouble one’s self to argue, where argument is not only loss of time but loss of temper and patience also. | The regeneration of this old myth is in its way an example of that longevity of all things beautiful, that may well point a moral to such scientific Alcibiades as have dared to speculate whether poetry can co-exist with science. When, as in this instance, a deeper science constantly verifies what a shallow science has denied—the eternity of the beautiful because it is beautiful—one need not trouble one’s self to argue, where argument is not only loss of time but loss of temper and patience also. | ||
<center>{{Style S-Small capitals| | <center>{{Style S-Small capitals|a glance at the evidence.}}</center> | ||
However, a glance at the evidence. Leydig and other eminent physiologists have so repeatedly stated the one isolated fact that the fresh retina in frogs and other animals has a reddish tinge, that the point is familiar to the most cursory reader of histological treatises. This fact alone, though significant, demonstrated nothing, and for years it lay fallow. Recently Professor Boll (''Zur Anatomie und Physiologie der Retina''), the celebrated Du Bois-Raymond and Professor Kühne (''Ueber der Sehpurpur'') have contributed very important data to retinal physiology, all of which have been printed within the last two years. It appears from these as yet untranslated essays and volumes that not only is the living retina always red, but that its color is subject to material alterations from the action of light. The coloration is, it should be premised, limited to the external aspect of the retinal rods, a considerable proportion of which, at least in the frog, are also of a bluish-green tinge. It exists in all animals having retinal rods, invertebrates as well as vertebrates. Boll having ascertained it in the cephalopods and an anthropods, and in all the fishes and amphibia brought under examination. In reptilians and birds the colored oil globules—most beautiful microscopic objects—interfere with its detection; and in the retina of the lizard and coluber natrix, which offer no retinal rods to | However, a glance at the evidence. Leydig and other eminent physiologists have so repeatedly stated the one isolated fact that the fresh retina in frogs and other animals has a reddish tinge, that the point is familiar to the most cursory reader of histological treatises. This fact alone, though significant, demonstrated nothing, and for years it lay fallow. Recently Professor Boll (''Zur Anatomie und Physiologie der Retina''), the celebrated Du Bois-Raymond and Professor Kühne (''Ueber der Sehpurpur'') have contributed very important data to retinal physiology, all of which have been printed within the last two years. It appears from these as yet untranslated essays and volumes that not only is the living retina always red, but that its color is subject to material alterations from the action of light. The coloration is, it should be premised, limited to the external aspect of the retinal rods, a considerable proportion of which, at least in the frog, are also of a bluish-green tinge. It exists in all animals having retinal rods, invertebrates as well as vertebrates. Boll having ascertained it in the cephalopods and an anthropods, and in all the fishes and amphibia brought under examination. In reptilians and birds the colored oil globules—most beautiful microscopic objects—interfere with its detection; and in the retina of the lizard and coluber natrix, which offer no retinal rods to scientific inspection, the nervous organism of vision being furnished with cones only. Kuhne was unable to discover any trace of coloring matter. It is absent in the hawk, behind the numerous spots furnished with oil globules, though present elsewhere, and the long and delicate rods of the owl (Athene noctua) are of a red or brilliant intensity not occurring in day-ranging animals, faint in its tint, and fading very slowly on exposure to light. In man the retinal rod was first observed by Zuckerkandl in examining the eyes of an executed criminal. Adler states that the color is absent in the eyes of blind persons. | ||
<center>{{Style S-Small capitals|influence of rays.}}</center> | |||
These are dull details, only adduced because they are the material symbols of a nascent new theory of the perception of color and probably of color blindness. The important fact is that the retinal rod is very sensitive to the action of light, persists after death for from fifteen to twenty-four hours if the eye is kept in a darkened room, but is rapidly whitened to a silvery lustre in a few minutes when exposed to ordinary daylight, although it may in some animals be regenerated after a post-mortem whitening by placing it in a dark box. | |||
The rapidity of this post mortem process depends upon the constitution of the light to which the retina is exposed, as well as upon its intensity. The rays of the spectrum between the yellow and the green possess, according to Kuhne, a peculiar influence in this respect, while the retina fades very gradually indeed when the rods are only exposed to the rays between the green and the violet end of the spectrum. As concerns the retina, red light darkens the rods until they exhibit a deep brown, which, in fading to red again under exposure to ordinary light, passes through a yellow stage. Yellow rays only render the color clearer; green rays of moderate intensity produce a purple alteration of the red rods, while rendering the bluish-green ones more brilliant; blue and violet have approximately, but in less degree, the same action as green, and ultra violet no action at all. It will be gathered from these data that retinal inquiry is likely to result in a new and well-grounded theory of color and of color perception—is a word, in the resolution of one of the most intricate problems of art criticism, that of the relation of color to nervous impression, feeling, sentiment and idea. | |||
<center>{{Style S-Small capitals|romance and reality.}}</center> | |||
But the picturesque aspect of the subject and the aspect in which it appeals to the imagination most specifically is, after all, the old question as to the possibility of obtaining persistent images on the dead retina; a question that has been settled affirmatively by Kuhne, who, having placed the decapitated head of a dead rabbit in a dark box, exposed it, in the first instance, to the light of a window of stained glass; then hardened the retina of the eye in a five per cent solution of alum for twenty-four hours in the dark and thus obtained a distinct and identifiable photograph of the window upon its red posterior aspect. Such images are scientifically styled optograms, and retinas thus treated can be dried and mounted for permanent illustration of the curiosities of retinal physiology. The question has been carefully tested recently with eyes of horses and dogs in the dissecting room of one of our colleges, with the result of finding, as maintained by German physiologists, that such optograms can be readily taken within one hour after the death of the animal, and developed by rapidly dissecting out the retina and immediately immersing it in a ten per cent solution of common salt. It is, therefore, one of the undeniable verities of science that, under favorable circumstances, it would be a matter of no serious difficulty to identify a murderer by this process, the fact furnishing only another illustration of the proverb that the strangest dreams of romance are often verified by reality. No doubt a Coroner's jury would treat the revelations of a dead retina with a little pardonable disrespect to begin with, but a little demonstration would suffice to convince even the most sceptical of professional jurymen.—''Philadelphia Telegraph.'' | |||