The mutant vestigial (vg), in which only the basal part of the wing is present, is one of the most familiar and intensively studied mutants in Drosophila melanogaster. Goldschmidt (1935) and Waddington (1940) made observations on the development of the vg wing but arrived at different conclusions as to the way in which the vg phenotype was produced. Goldschmidt proposed that the reduction of th...

By utilizing a nanometer ultrafast electron source in a point projection microscope we demonstrate that images of nanoparticles with spatial resolutions of the order of 100 nanometers can be obtained. The duration of the emission process of the photoemitted electrons used to make images is shown to be of the order of 100 fs using an autocorrelation technique. The compact geometry of this photoe...

A dedicated Scanning Transmission Electron Microscope is ideally coupled with the energy dispersive x-ray and electron energy loss spectroscopies to obtain information about the chemical composition, morphology and electronic structure on the nanoscale. With several signals being available simultaneously with the pass of a subnanometre-sized beam, this instrument can answer questions from a bro...

RNA containing yolk nuclei from the surf clam Spisula solidissima have been studied with the light microscope and with the electron microscope. A variety of structures can be seen with both and a correlation can be made between bodies studied with the electron microscope and those studied with the light microscope. The electron microscope shows many of these structures to be composed of double ...