The study of the peripheral distribution of the right bundle branch in bovine, dog's, goat's, lamb's, and human hearts demonstrates an anatomical basis for the production of varying degrees of right bundle-branch block on operative incision of the anterior wall of the right ventricle. The left branch of the cardiac conducting system, with its transventricular cavity conducting bundles to the papillary muscles and the ventricular wall in bovine, dog's, goat's, lamb's, and human hearts, offers an anatomical basis for varying degrees of disturbance in left ventricular conduction due to operative incision or instrumentation in the left ventricle. Comparative anatomical studies in man and animals show conducting fibers which traverse the ventricular cavities in structures previously termed pseudotendons or false chords. In man, the existence of these transventricular cavity conducting bundles has not been emphasized, probably because of the traditional methods of opening the heart at autopsy. The combined electrocardiographic and anatomical concepts provide a useful background for caution in open-heart operation, lest stretching during manipulative procedures or cutting these peripheral conducting bundles produces irrevocable conduction-damage.

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pattern was presented in each modality) show less than 15 percent reorganization of the pattern when patterns began at nonpreferred start points. Therefore, sequences of either left-right or modality elements were perceived as structured patterns, but sequences in which the left-right elements were 'embedded' in an irrelevant alternation of modalities (every two, four, or eight elements) were organized by modality, not by pattern structure.Differences in the rate of identification of patterns are determined by the modality or pair of modalities used to present the pattern. The rate of identification of patterns presented in pairs of modalities is not necessarily slower than identification of patterns presented in one modality. Only the A-T combination produced poorer performance than its component modalities, and for this combination, performance was poorer whether the elements of the stimulus were organized by modality (method two) or by pattern structure (method three). The physiological similarity of the A and T modalities (7) may cause confusion when the pattern elements-presented in these modalities must be integrated. Alternating between the T and V modalities, and especially between the A and V modalities, seems to produce a sensation of "snapping back and forth" between modalities which is absent when alternating between the A and T modalities.

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