On the nature, locality and optical phenomena of muscae volitantes / by James Stark.

Date:
[1843?]
Catalogue details

Licence: Public Domain Mark

Credit: On the nature, locality and optical phenomena of muscae volitantes / by James Stark. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    ON THE NATURE, LOCALITY, AND OPTICAL PHENO- MENA OF MUSC^ VOLITANTES. By James Stark, M. D., F. R. S. E. Fellow of the Royal College of Physicians of Edinburgh. (^From the Edin. Med. and Surg. Journal, No. 157.) During the last few years several essays have been published, both in this country and on the continent, with the view of explain- ing the causes and phenomena of the muscce volitantes, and, in addition to this, almost every work treating of diseases of the eye, has de- voted a separate chapter to the same subject. The mass of facts and of theories thus brought forward has been far from throwing much light on this interesting subject, almost all failing to demon- strate the truth of the theories they advance ; and those who do de- monstrate that which they describe depends on a particular struc- ture existing in the eye, describe what is not a musca volitanx, and has none of the characters belonging to that body. Having paid no inconsiderable attention to this subject,—having, besides, had an opportunity of studying the complaint more than once in my own ])erson, and having taken advantage of this circum- stance to investigate fully its phenomena, causes, and locality, I have been enabled to arrive at conclusions which will explain every phenomenon, and render true mtiscce volitantes capable of being at once distinguished from those fixed specks, nebulae, and the mottled indistinct vision of amaurosis and partial paralysis of the retina, which, even by the most eminent writers on this subject, have been mistaken for them. As considerable confusion seems to exist, even in the writings of the very latest writers, as to what are muscce volitantes, it is quite necessary that this be fully understood before we attempt an ex- planation of the phenomena, or assign their place in the visual-organ- It was from not attending to this that even Sir David Brert'ster ap- pears to have described, as a ?misca volitans, one of those fixed specks in the eye which have been so often confused with and mistaken for the objects in question. Of all the late writers M. Prevost in his learned essay printed in the Memoires de la Societe Physique et d'Histoire Naturelle de Geneve, has given the most accurate and characteristic description of muscce volitantes ; laying down characters, which, if attended to, will serve to distinguish them from all other kinds of specks met with in vision. On looking fixedly (says M. Prevost) at a point which is well illuminated, (the sky,) and taking the fixed point at A