Endobronchial lavage was performed on eight smokers and eight nonsmokers. Centrifugation of lavage fluid produces a sediment consisting of two layers, a lower compact brown layer containing cells and a n upper flocculent white layer. The brown layers from the smokers were greater in volume than those from the nonsmokers. Macrophages constituted about 93% of the cells from the smokers and about 63% of the cells from the nonsmokers. These data suggest that more free macrophages occur in the lungs of smokers than nonsmokers. In addition, many of the macrophages obtained from the smokers were filled with cytoplasmic inclusions. The volumes of white layers from the smokers were smaller than those from the nonsmokers. One white layer obtained from a nonsmoker was examined in a Wilhelmy balance and proved to be surface-active. This may suggest that surface-active material, pulmonary surfactant, is reduced in lavage fluids from smokers.

Mitochondria in early spermatids of many insects aggregate and form a round body, the nebenkern. The nebenkern undergoes a structural differentiation and then divides into two separate equal-sized bodies. In the present study, nebenkerns of Murgantia histrionica, a Hemipteran insect, were reconstructed using electron micrographs of serial sections to determine how the mitochondria transform into the two separate bodies.Newly formed nebenkerns are made of one piece, an anastomosis of rod-like segments. Some segments interconnect to join networks of rings. Each network interlocks with another similar network, but networks which interlock are connected with each other by other segments of the nebenkern. Later, the entire nebenkern is made of two unconnected and interlocked networks of rings. The nebenkern appears to remain bipartite during subsequent differentiation. Since the two pieces are interlocked, breaks must occur before the pieces can separate. As breaks occur, each network transforms into a set of curved sheets, producing a nebenkern made of four concentric layers. The three outer layers are each made of two curved sheets which surround a bipartite central core. The surface sheets meet at a furrow in the surface of the nebenkern; segments in each layer are roughly symmetrical with each other about the plane in which the furrow lies. Rod-like segments join alternate segments. The number of layers then decreases to three, and later, to two. These nebenkerns resemble four-layered nebenkerns, but fewer connections between alternate segments are present. The two pieces constituting the nebenkern probably separate after most of the latter connections disappear. Hypotheses to account for the observed changes in nebenkern structure are presented.Studies with the light microscope have shown that mitochondria in early spermatids of many insects aggregate and form a round body, the nebenkern (Meves, '00; Gatenby, '17; Bowen, '22a; Pollister, ' 3 0 ) . In some Hemipterans, the mitochondria are long filaments before and during aggregation, but the newly formed nebenkern is dense and filaments can no longer be distinguished with the light microscope (Montgomery, '1 1 ; Bowen, '22a,b). Soon clear spaces appear within the nebenkern and the nebenkern resembles a collection of granular and rod-shaped mitochondria. Then the clear spaces seem to coalesce into several concentric layers (Bowen, '22b). Gradually the layers decrease in number and, as the last inner layer disappears, the nebenkern divides into two separate equalsized bodies.In single sections viewed with the electron microscope, newly formed nebenkerns appear to be aggregates of the separate mitochondria observed at telophase 11 (Tahmisian, et al., '56; deRobertis and Raffo, '57; Yasuzumi and Oura, '65). However, the observation that segments of nebenkerns made of concentric layers actually connect with each other to form two pieces was made in studies of short series of sections of nebenkerns in the butterfly Pieris (Andre, '59a, '62) and in the bug M...

Structural features and microorganisms associated with rhizosheaths (sand grain root sheaths) of Oryzopsis hymenoides were examined by scanning electron microscopy. Rhizosheath structure appears to depend primarily on the extent of root hair growth and the bonding between root hairs and sand grains. Several sources of bonding agents are suggested, but plant products may be the most important. Microorganisms, usually rod forms, were frequently observed in association with coatings, resembling mucilage, on root surfaces and root hairs. The fungus Olpidium and unusual bacterial forms resembling Ancalomicrobium and Hyphomicrobium were observed on or near root surfaces. Mycorrhizae were not observed nor could the presence of actinomycetes be attested to.