Various electron lens systems of electron microscope excited with permanent magnets are reported.
Characteristics of double gap lens with three pole pieces in one-stage lens system, design and experimental results of parallel and combined type in two-stage lens system and at last the constructions of magnetic circuit and characteristics of parallel-series and the other types in three-stage lens system are stated.

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The following conclusions have been obtained after the c eful research on the change taken in the fine structure of liver cells which was caused by the various osmotic pressure of fixative, namely the changing of sucrose concentration from 0.05 to 0.88 M. and NaCI concentration from 0.45% to 1.8%.
1). In case of the liver cells, the Mitochomdrion and Endoplasmi reticulum show notable transformation with the osmotic pfessure of fixative, i. e. by using the hypertomic solution, the Mitochondria take either long-oval form or a rod-shape. While it expands with the hypotonic solution and takes almost a spherical form. As the result, the network constructing the Mitochondria expands, breakd up and takes a crista (septa) shape. But it is-noted that the Endoplasmic reticulum shows the remarkable deformation in the three-layers strucure by the use of the hypotonid solution.
2). By the use of hypotomic fixative on NaCl concentration, it is also noted that the .Mitochondria' takes a long-oval form. And on the outer two layers of the three-layers structure of the Endoplasmic reticulum and the Mitochondria, i.e., on the electron denselayers, the move electron-dense granules of 15-20mμ. can be seen regularly arranged.
3). From the above experimental results, we have come to the conclusion that the fixative made from 1 per cent osmium tetroxede, 0.25 M. sucrose and 1/100M. phosphate buffered salution, causes the least transfo, mation, and is considered the fittest.
But further comparisan with the hypotonic solution will be desired.

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The fine structure of mitochondria and endoplasmic reticulum in normal rat liver cells have been studied, being fixed by 1% osmium tetroxide dissolved in next mediums.
(1) 1/30 M phosphate buffer. (2) 0.25 M sucrose solution buffered with 1/100 M phosphate. (3) 0.9% NaC1 solution buffered with 1/100 M phosphate.
The following conclusions have been obtained.
1. In mitochondria, the three layer structure (two outer electrondens layers and bright inner layer) have been .observed. The width of the outer layer was 50AÅ; the layer demonstrated electrondense granules (diameter: 50Å). The bright inner layer was 70Å in width. Mitochondria -are constructed of the network of lamellae observed on the three layer structure. When mitochondria have swelled in a hypotonic solution, the reticular shaped mitochondria are extended by increasing of immobilized water, and these electron-micrographs are observed on mitochondrial membrane and. cristae mitochondriales.
2. Endoplasmic reticulum have been constructed regularly of three layer structure; two outer electrondense layer and bright haner layer. The two outer layer are of a smooth layer (width: 50Å) and electrondense particles [cytoplasmic membrane particle (Siöstrand)]. The bright inner layer is 70Å in width. This three layer structure will be constructed by double layer of liponucleoprotein. Being fixed in a hypotonic solution and being decreased in concentration of protein this three layer structure will have been deformed to a sac form.
The models of mitochondria and endoplasmic raticulum are assumed as Fig.5.

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Fxperiments Were made with the parotid gland taken from a dog in starved state.
(1) Acinar epithelial cells of the parotid gland were characterized by the existence of a number of endoplasmic reticulum. In the cytoplasmic matrix of these calls there were observed a large number of droplets of low density which contained irregular-shaped granules of high density. Moreover, an interdigitating structure was also observed between two adjoining cells.
(2) Epithelial cells of intercalated ducts showed so simple structures that they were scanty of endoplasmic reticulum, cytoplasmic granules and mitochondria.
(3) Epithelial cells of striated tubules were characterized by parallel arrangement of mitochondria.Double-lined membraneous structure, going parallel among these mitochondria, were observed to be continued with the cell membranes of the cell basis.

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Every fractions and supernatnat, obtained by the cell fractionation technique from liver cells, were observed with an electron microscope in oder to sturdy the correspondency of these fractions to fine structures of liver cells.
In a large granular fraction which were fixed with 0.5% OsO4 0.5M sucrose solution, a great number of mitochondria, mostly of a reticular shape with a three layer structure, were observed. Being fixed with a hypotonic solution, however, the mitochondria were swollen.
The microsomes, obsrved in supernatnant, showed frequently a flat or lamellar form interwoven by tiny particles (diameter: 15-20mμ).
Ultrathinsections of microsomal and ultramicrosomal elements showed also a lamellar or vesiclar form coposed of the three layer structur. The small spherical shape, having a central bright area, was also observed.
The resuspended microsome deformed itself into a sac form.
The homogenizing products of endoplasmic reticulum were mainly included in microsomal and ultramicrosomal fractions.

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The particle sizes of various powders measured by the sedimentation, adsorption and air-permeability method were compared with the results by the electronmicroscopy. In the case of the powders having especially uniform shape and size, all of the values of mean particle sizes by various methods, were almost same. For the common powders, however, the values by various methods did not agree. From observation of the particle shape with the electron microscope, it is possible to explain the difference of the apperent particle sizes by various methods has the relation with other properties.

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