Outlines of scientific anatomy : for students of biology and medicine / by Wilhelm Lubosch ; translated from the German by H.H. Woollard.

Wilhelm Lubosch

Date:: 1928

Credit: Outlines of scientific anatomy : for students of biology and medicine / by Wilhelm Lubosch ; translated from the German by H.H. Woollard. Source: Wellcome Collection.

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$a microscope is that in the microscope particles are seen according to their form, while in the other only an optical proof of their presence is obtained, without any resemblance to their form. The above [para. 100] mentioned limits of optical resolution of particles is, therefore, not as such an optical proof of particles. Mass particles of very much smaller size than half the wave length of light are optically provable. Therefore, one measures the ultramicroscopic elements not by “/a,” but by double-^ “ yLtyu, ” in which a/x = l,000 /x/x. In general, the following divisions of size apply :— (1) Particles which are demonstrable with the microscope, microscopic particles or microns (= 200 fi/i). (2) Particles which are not demonstrable, but only optically provable, ultramicroscopic particles or ultramicrons from 200 yu/x up to molecular size. {a) Those which may be proved as individual particles; sub- microscopic particles or submicrons (to 4 /jl/jl). (b) Those which are not provable as individual particles, amicroscopic particles or amicrons. The latter can excite light impressions in their movements on one another through their refracting power. With the observations of the smallest submicrons, we already reach the limits of the larger molecular units. Since the average size of an individual molecule is given as 0*6 /x/x, groups of six molecules, situated on one another, brought into the ultramicroscope arouse optical impressions. We can, therefore, by means of the wonderful instrument constructed by Zsigmondy and Siedentopf, actually peer right into the world of molecules. The refracted forms visible in the ultramicroscope of submicrons and amicron groups appear in different colours and different degrees of clarity and show dancing, bouncing Brownian molecular movements. Whilst the ultramicroscopic investigation of larger (suspensions) colloids (colloidal metal solutions) has been much pursued and has given important results, unfortunately the investigation of protoplasm and tissue by the ultramicroscope is only at its beginning (E.Raehlman, Michaelis) and has not been carried far since a technique for the preparation of specimens which suffices for the ultramicroscope is not yet accomplished, and the few which can be studied in erythrocytes, leucocytes, and granules, do not confirm the conclusions gained from the usual microscopic study. Most recently a satisfactory method has been worked out, and through investigation in the dark- ground field a glimpse into leptonomorphology has been obtained (plasmodial form of connective tissue, Heringa, structure of fibrillse, Schmidt).$