Photographs of Serial Sections of the Lung projected rapidly in Sequence using 16-mm. Film

THE course and condition of small branching structures within a sample block of histological material cannot be appreciated with ease or demonstrated very successfully. With lung tissue, for example, casts and coloured, or radio-opaque, injections of the bronchial and vascular trees have been of great assistance; but these methods usually entail the removal or clearing of surrounding structures. Alternatively, serial sections may be observed en masse by serial reconstructions, thus overcoming, to some extent, the fact that the direct examination of serial sections in sequence is too slow for a full understanding of the plan of the tissue as a whole.