Light-microscope slides ( 3 in. x 1 in.) bearing Gram smears of Erysipelothrix rhusiopathia, or Staphylococcus aureus, after preliminary examination under the light-optical microscope (LM), were cut down in size, glued onto specimen stubs, coated with gold and examined in the scanning electron microscope (SEM). These preparations served as a control for investigations into bacteria-cell junctions in tissue.Cover-slips from stained sections of staphylococcal or swine erysipelas endocarditis mounted on 3 in. x 1 in. microscope slides (which had been intensively studied previously with conventional light microscopy) were floated off by immersing the slides in xylol. After dehydration of the tissues on the slides, the preparations were treated similarly to the Gram smears, and were examined with the SEM. Lesions of endocarditis were thus examined, and the information gained from these preliminary examinations shed new light on the pathogenesis of the disease. This information had not previously been available by any other technique. Because of this, and in view of the simplicity of preparing sections for scanning electron microscopy, it is suggested that the SEM might be a useful tool to be applied to routine histological sections.

Summary 1. Three‐quarters of the heart lesions in 21 pigs with spontaneus endocarditis yielded E. rhusiopathiae either in pure form (from 2/3) or in mixed culture with streptococci (from 1/3). Only four of twenty isolates were pure cultures of streptococci, indicating the possible prevalence of erysipelas endocarditis in pigs in Southern England. 2. Anitschkow myocytes demonstrated in the lesions of valvular endocarditis and myocarditis are, in all probability, cells of myofibre origin and occur in these cases as a response to direct bacterial injury. 3. Lesions of arteritis, bacterial embolism and infarcts in the myocardium, lend support to a possible embolic origin of the valvular lesions. Zusammenfassung Bakteriologische und pathologische Untersuchungen zur spontan auftretenden Endokarditis der Schweine 1. Aus Dreiviertel der Herzläsionen konnten Rotlaufbakterien entweder allein (von 2/3), oder zusammen mit Streptokokken (von 1/3) herausgezüchtet werden. Nur vier von zwanzig Isolierungen waren Reinkulturen von Streptokokken. Dies weist auf das Vorherrschen der Rotlaufendokarditis der Schweine im Süden Englands hin. 2. Anitschkow Myocyten, die in den Läsionen von Klappenendokarditis und bei Myokarditis nachgewiesen werden, sind höchstwahrscheinlich myofibrillären Ursprungs und in diesen Fällen Anzeichen direkter Bakterieneinwirkung. 3. Die öfter auftretenden Arteriitiden, Bakterienthromben in den Gefäßen und Myokard‐Infarkte sprechen für eine embolische Genese der Klappenveränderungen. Résumé Observaations bactériologiques et Pathologiques de l'Endocardite arrivant spontanément chez le Porc 1. Dans les trois‐quart des lésions cardiaques etudiées, E. rhusionpathiae pouvaient être isolés en la forme pure (dans 2/3 des cas), et en combinaison avec streptocoque (1/3 des cas). Dans seulement deux des vingt souches etudiées, streptocoques etaient trouvés en la forme pure, indiquant la prévalence possible des erysipelas d'origines endocardites chez l'espèce porcine soumise aux conditions du Sud de l'Angleterre. 2. Les myocytes d'Anitschkow démontrés au niveau des lésions valvuläres de l'endocarde et du myocarde sont, fort probablement, des cellules d'origines myofibreuses et se présentent dans ces cas, comme étant dû à l'action directe de la bactérie. 3. Les lésions artériennes, l'embolisme bacterie et les infactus rencontrés au niveau du myocarde, nous portent a croire que les lésions valvulaires sont d'origines emboliques. Resumen Investigaciones Patológicas y Bacteriológicas en Casos Espontáneos de Endocarditis en Suinos 1. Des tres cuartas partes de la leisones del carazón, se aislo E. rusiopatiae. De los terceras partes se aislo en forma pua, y en una tercera parte de los casos, en cultivo mezclado con streptococos. Solo dos de viente aislamientos dieron cultivos puros de estreptococos, indicando la posible prevalencia de endocarditis producidas por erisipelas sobre las endocarditis causadas por estreptococos en cerdos en la sur de Inglaterra. 2. Los miocitas de Anitschkow demonstrados en las leisones de endocard...

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Summary The instrumentation necessary for precise and fast correlation of images derived from a light optical microscope (LM) and a scanning electron microscope (SEM) operated in the reflective mode, is described. The specimens can be mounted on standard microscope slides (25 × 75 mm), SEM‐stubs (12 mm ø), or on transmission EM grids (3 mm ø). The instrumentation consists of two parts: an attachable precision stage for an LM, and an attachable slide carrier for the stage of an SEM. By taking into account the vernier readings of the stages of both microscopes (LM and SEM), identical particles in a specimen can be found instantaneously under either microscope. Therefore it is concluded that the use of this instrumentation in correlative microscopy (LM → SEM → LM) is time saving, and especially recommended on fragile biological specimens, which may deteriorate rapidly under the electron beam of an SEM.

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