ORIGIN AND HISTORY 



usually initiated by a technical break- discovered by Pollender in 1849. Establish- 

 through, followed by a whole series of dis- ment of histology as a special field by Kolli- 

 coveries in new fields not accessible by the ker in 1852. The first microtome was de- 

 optical means in use before. signed by Welcker in 1856. Lactic acid 

 This mode of progress is well" known from bacteria were discovered by Pasteur in 1857. 

 other fields of technical and scientific en- Introduction of antisepsis based on micro- 

 deavor but it is especially intriguing to out- scopial evidence by Lister in 1864. Methods 

 line the respective phases in the development of selective staining developed for tissues by 

 of a field the study of which was denied so Gerlach in 1858 and for bacteria by Weigert 

 long to unaided human senses. In the field of in 1875. 



microscopy the following periods can be Fourth Period: From 1878 to 1931. Intro- 

 recognized, in each of which the technical duction and further development of the 

 progress and the achievements are named: homogeneous immersion, ^c/iteyemen^s; Gon- 

 First Period: From about 1600 to 1723. orrhoea cocci found by Neisser in 1879. 

 Invention of the microscope. Discovery of Leprosy germs seen by Hansen and typhus 

 the law of refraction by Snell and Descartes, germs by Ebert in 1880. Malaria parasites 

 1637. Establishment of geometrical optics seen within red blood cells by Laveran in 

 by Fermat, Newton, Huygens and Euler. 1880. In the two decades from 1880 to 1900 

 Achievements: Discovery of the capillaries numerous other pathogenic protozoa and 

 by Malphigi in 1660. Discovery of plant bacteria were discovered, as tuberculosis and 

 cells in fossil wood by Hooke in 1664 and cholera by Koch in 1882, plague by Kitasato 

 the first magnified drawings of small ani- in 1894, tetanus by Nicolaier in 1884, Sj^h- 

 mals, the flea and the louse, by the same in ills by Schaudinn in 1905, of foot and mouth 

 1665. Discovery of the mammalian ovarian disease using ultraviolet light by Frosch in 

 follicle by De Graaf in 1672. Descriptions by 1924. 



Leeuwenhoek of protozoa in 1674, striation Fifth Period: From 1931 to the present 

 of muscle fibers in 1682, bacteria in 1676, time. Invention and development of the 

 spermatozoa in 1672, yeast cells in 1688, electron microscope. Further development of 

 leukoc3rtes in 1689, axon and sheath of the light microscope into numerous new 

 nerve fibers in 1717. models for special applications. Achieve- 

 Second Period: From 1723 to 1830. Al- ments: The first micrographs of virus cor- 

 most no progress from Leeuwenhoek's death puscles, not visible with the light microscope, 

 at the beginning of this period until the end. were made by Kausch and Ruska of the 

 This was the high time of the hobby micro- tobacco mosaic virus in 1939. 

 scopist, best exemplified by the title of a It is obvious that these periods overlap 

 book which appeared in 1763. It is Leder- each other widely and many a discovery 

 miiller's "Mikroskopische Gemiits- und might just as well be assigned to the preced- 

 Augenergotzung," which might be trans- ing or the following period. However, a gen- 

 ial ed by "Microscopical Pasttime for Eyes eral pattern is certainly recognizable, 

 and Soul." 



Third Period: From 1830 to 1878. Inven- references 



tion and further improvements of achro- Magie, W. F., "A Source Book in Physics," Mc- 

 matic lenses. Achievements: Fermentation is Graw Hill Book Co., New York, 1935. 



explained from the action of living cells by Sakton, G. "A History of Science," Harvard 

 ^ . , 1 , rr^ • -.oo^ rT^^ n j_ 1 University Prcss, 1 . vol . 1952, 2. vol . , 1959. 



Cagniard de la Tour m 183/. The first clear g^^^^^^ ^^ "Ancient and Medieval Science," 



description of the division of the cell nucleus University of Pennsylvania Press, Philadel- 



is given by Leyden in 1848. Anthrax bacteria phia, 1953. 



463 



