MICROSCOPE, (ihoevic, small,andaxovw, to look at,) an instrument for aiding the eye in the examination of minute objects. Although a description of the structure and uses of this instrument cannot be considered as strictly belonging to a work like the present, yet the knowledge of them is so closely connected with its general objects that it has been deemed ad visable to make it an object of special attention. The applications of this instrument to the pur poses of the anatomist and physiologist are so numerous, that a whole treatise might easily be written upon them alone. We are not aware, until we come to think on the subject, how much of our knowledge of what takes place within the living body is dependent upon its revelations. To take a familiar illustration,— the capillary circulation might be, in some degree, guessed at by tracing the ramifications of the bloodvessels as far as they could be dis cerned with the naked eye; but we shoulikhave known extremely little of it without the micro scope. Our whole knowledge of the early processes of development in plants and animals is gained by the same assistance. Not only is
much of that, which ranks as established ana tomical or physiological truth, founded upon microscopic researches, but similar researcnes, which are being prosecuted at the present time, are yielding a harvest of discovery still richer in amount, whilst not less important in its cha racter.
We propose, in the present article, to take a general view of the principles, optical and me chanical, which are concerned in the construc tion of the microscope; and then to give an outline of the results of some of the most re cent enquiries in which it has been profitably employed,—confining ourselves chiefly, how ever, to those which concern the origin and formation of the principal organized structures. If it be thought that the former portion is too much extended, we have only to say, that we know of no single treatise to which we can refer our readers for a large part of the informa tion which we desire to convey ; and that we have therefore judged it desirable to make the article complete in itself.