Abstract
One of the things to be desired in the study of microincinerated sections is an accurate means of estimating the relative quantities of inorganic salts in various cells. Such a method would permit a quantitative comparison of tissues taken from animals subjected to experimental procedures with similar normal cells. Furthermore it would be possible to study such processes as normal growth and differentiation in a more exact manner than the microincineration technique has permitted. A quantitative method also has many advantages in the examination of pathologic tissues and comparable normal ones. The technique for quantitative photography of incinerated sections devised by Schultz-Brauns 1 has many points to commend it; but it is, in the final analysis, a procedure which depends on the visual judgment of the observer. It seemed advisable, therefore, to develop a method which would be free from this objection.
The nature and distribution of the inorganic salts in cells and tissues has been described.2, 3 The appearance of the ashed preparations in darkfield illumination is that of hoar frost on a blackened surface. With this means of illumination only the ash of the section is revealed by light reflected from the surfaces of the individual particles of mineral. It is assumed, therefore, as the particles are approximately the same size and nature, that the more mineral present in the microscopic field the greater the quantity of light reflected into the eye of the observer. This assumption has been checked, in as far as possible, by examining colloidal solutions at different dilutions with the darkfield microscope with the result that given a constant source of light the intensity of the beam emerging from the ocular is roughly proportional to the number of particles in the microscopic field.
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