features of rat aortic cells during development. An electron microscopic,

X-RAY GAUGING EQUIPMENT

This chapter surveys selected highlights of the evolution of modem ideas about the molecular organization of biological membranes. Thesurvey is innosensecomplete, and references 1-14 may be consulted for more details on the topics covered here. Many important topics left almost or completely untouched include membrane transport (15-21), black lipid films (22-31), and many aspectsofmembrane biochemistry (32-35).

Present investigation was carried out to study the ultrastucture and mineral composition of scales of Barilius bendelisis from the selected sites on the Kaushlya river adjoining Panchkula (HR). The scales of Barilius bendelisis were cycloid scales and can be divided into anterior, posterior and lateral regions. In this species, the focus was indistinct and lied in the anterior part of the scale and the inter-circular space was maximum in the posterior region and minimum in the anterior part. The circuli were with lepidonts. Radii were classified into three types viz., primary radii, secondary radii and tertiary radii. In the present study one distinct annulus was reported, which indicated that this fish belonged to one year of age class. Six minerals were reported from the scale of the fish under report viz., Calcium, Carbon, Oxygen, Sodium, Potassium and Phosphate when different regions of the scale were subjected to energy-dispersive X-ray microanalysis (EDX). It can be concluded that the circuli and the posterior part of the scale contains maximum percentage of minerals as compared to the other regions of the scales.

An original image processing procedure that reconstructs the surface topography of a hea-vy metal- shadowed replica from a digitized micrograph is presented. The theory of this method is established and its limits are discussed. The usefulness and validity of the median filtering algorithm used in the data reduction are shown. The entire procedure has been implemented in a small 16 bit minicomputer. The method has been used to study the rough surfaces of copper, silver, magnesium and gold deposits by autocovariance functions of surface profiles. The results show that good recons-tructions of extended surface replicas are obtained. Several new methods of improving the reconstruction process have been tested and are briefly presented. Under goodexperimental conditions the lateral resolution was 50 A for an overall field size of 40.000 A. This shows that our method may have important applications besides the study of alterable metallic surfaces. 11111111

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The Scanning Confocal Electron Microscope, is an instrument which permits the observation and characterization of sub-surface structures of thick, optically opaque materials at nanometer level resolutions. The instrument merges the capabilities of the scanning, transmission and x-ray microscopes

Electron microscope investigation of silver halide crystals

of HD, one could plot universal grain distributions for specimens with radioactive sources of various shapes. The use of HD and the universal curves in interpreting radioautograms is discussed. Electron microscope (EM) radiaoutography introduced by Liquier-Milward (1956) is now used routinely in many

The transmission electron microscope is now used in a great variety of mineralogical nd petrological contexts, The development of such applications over the past thirty years is illustrated by reference mainly to studies on serpentine and amphibole minerals.