818 ANATOMY [HISTORY. into practice and improved by the two MM. Chevalier of Paris. About the same time Dr Goring in London, with the aid of Mr Tulley and Mr Pritchard, constructed com pound microscopes upon a similar principle. By the labours of these practical opticians, and the suggestions of various scientific persons, as Sir John Herschel, Sir Richard Airy, Mr Barlow, one great defect of the compound microscope was obviated. The effects of spherical aberration were in the next place overcome in a very simple manner by the experiments of Mr Joseph Jackson Lister, who had early observed that the combined achromatic object-glasses devised by Selligues were fixed in their cells with the convex side foremost, a most improper position, as it renders the spherical errors very great. This gentleman found, after various trials, that, by placing three or more achromatic glasses with their plane surfaces directed foremost, it was possible to correct completely all spherical aberration. This fact was made known in the beginning of the year 1830 ; and by its application the compound microscope was brought to a high degree of perfection as an achromatic instrument in 1831 and 1832, and became the means of affording valuable assistance in anatomical inquiries. The use of the microscope in anatomy, which had in the times of Malpighi, Leeuwenhoeck, William Cowper, Baker, Fontana, Hewson, and the second Monro, been much cultivated, but had afterwards, from the imperfection of the instrument and the illusions to which it not unfre- quently gave rise, been neglected, now became so general and so necessary, that since the year 1832 minute struc tural anatomy has been, if not created anew, at least most thoroughly revised. The amount of knowledge has been enormously increased ; that which was already pos sessed has been rendered greatly more accurate and precise. Micro- It is impossible in this place to name the authors of all scopic the valuable monographs which have appeared during the anatomy. p agt f or ty veargj but those who have especially advanced the progress of our knowledge of the minute structure of the tissues and organs may be referred to. Johannes Miiller in 1830 published an elaborate commentary on the minute structure of the glands, the first work in which the anatomy of these organs was examined and elucidated in a comprehensive and systematic manner. Ehrenberg explained the structure of numerous infusoria, and disclosed the peculiarities of many other structures, animal, vegetable, and mineral, which had previously eluded the most skilful researches. Francis Kiernan, in 1833, gave the first correct account of the minute anatomy of the liver. Schleiden in 1838, and Schwann in 1839, published most important generalisations on the cellular structure of vegetable and animal organisms. Martin Barry communi cated new facts on the structure of the ovum and on the structure of cells generally. John Goodsir laid great emphasis on the office of the nucleus in the nutrition, growth, and reproduction of cells, and on the arrangement of the cells within an organism into departments or territories. Virchow, by his researches into the connective tissues, has still further developed the idea of the cellular structure of the animal organism, and the importance of cells in the performance of physiological and pathological processes. Lionel Beale attributed both to the nucleus and to the substance of the cell immediately surrounding it import ant functional properties. Max Schultze showed the identity in nature between the sarcode substance of the lower animal organisms and the contents of the cells in the higher animals, and applied to these substances the common term proto plasm, which had previously been introduced by Hugo von Molil to designate a similar material in the vegetable cell. The minute structure and development of bone has Leen carefully investigated by J. Goodsir, W. Sharpey, H. Miiller, C. Gegenbaur, and A. Ko Uiker ; that of muscle by Bowman, Kolliker, and Sharpey; of nerve by Schwann, Rcmak, Stilling, Gerlach, Lockhart Clarke, and Deiters ; of cartilage by Schwann and Schultze ; of the" blood and blood-vessels by Henle, Gulliver, Quekett, Paget, and Wharton Jones ; of the mucous membranes by Bowman ; of the serous membranes by Henle, Recklinghausen, Ludwig, and Klein ; of the teeth by Retzius, A. Nasmyth, J. Goodsir, J. Tomes, R. Owen, Czermak, Huxley, and VValdeyer. The structure of the lungs has been investigated by Addison, Rainey, and Rossignol; of the kidney by Bowman, Henle, and Schweiggerseidel ; of the liver by Beale and Hering ; of the spleen by Sanders, Gray, Billroth, and W. Miiller ; of the testicle by A. Cooper, Kolliker, and Henle ; of the ovary by Pfliiger and Waldeyer ; of the thyinus by A. Cooper and Simon ; of the stomach and intestines by Kolliker, Brinton, and Frey ; of the placenta by Eschricht, Reid, Sharpey, Goodsir, Van der Kolk, Virchow, Farre, Priestley, Rolleston, Ercolaui, and Turner ; of the organs of sense by Henle, Bowman, His, H. Miiller, Schultze, Corti, Reissner, and Deiters. The general results of the labours of these and other investigators have been from time to time incorporated into systematic treatises on microscopic anatomy, of which reference may more especially be made to those prepared by J. Berres, F. Gerber, A. Hill Hassall, A. Kolliker, W. Sharpey, W. Bowman, F. Leydig, Frey, and S. Strieker. Side by side with these inquiries into the structure and development of the tissues, the evolution of the embryo out of the fertilised ovum has been carried on. Purkinje, Von Baer, Coste, Wharton Jones, Valentin, R. Wagner, Rathke, J. Miiller, Prevost and Dumas, Martin Barry, Reichert, Bischoff, Kolliker, Vogt, Allen Thomson, Owen, Von Siebold, Dujardin, Milne-Edwards, Claparede, Agassiz, Huxley, Kitchen Parker, and Kowalevsky have all contri buted important memoirs on various branches of embryology. Comparative Anatomy, which during the 18th century was Com] diligently cultivated by Daubenton, Pallas, Haller, Buffon, tive John Hunter, and the second Monro, has become during the anatc present century a subject of increased interest, from its inti mate connection with the sciences of zoology, physiology, and geology. It has consequently been studied with great zeal and assiduity, and multitudes of monographs, as vell as numerous systematic treatises on the anatomy both of the vertebrata and invertebrata, have been published. To name even a tithe of the workers and authors who have added to our knowledge of the facts of comparative anatomy Avould occupy considerable space. It may suffice to refer to those whose writings have contributed most materially to the advance of the science. In France, Cuvier, Dumeril, the Saint-Hilaires, Blanchard, De Blain- ville, H. and Alphonse Milne-Edwards, Gervais, and Gratiolet ; in Germany, Meckel, Tiedemann, Von Baer, Spix, Martius, Bojanus, Otto, Carus, J. Miiller, Leuckart, Gegenbaur, and Plaeckel ; in Sweden and Denmark, Rctzius and Eschricht ; in Holland and Belgium, Van der Kolk, Vrolik, and Van Beneden ; in America, Agassiz, Wyman, and Burmeister; in Great Britain, E. Home, A. Carlisle, R. Grant, Richard Owen, J. Barclay, R. Knox, J. Goodsir, G. Busk, Rymer Jones, W. B. Carpenter, T. H. Huxley, G. J. Allman, W. H. Flower, St George Mivart, and J. Murie are names identified with one or more branches of the subject. The investigations into the form and structure of animals have led anatomists to search for parts in one animal which correspond with parts in other animals in their mode of development and arrangement, and to evolve from their researches general doctrines of organic forms. The conception entertained by Goethe of the
presence of a pre-rnaxillary element in the human upper
