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Photoelectric plethysmographs for the fingers and toes are described which use electrocardiographs for the recording and which have definite advantages in routine clinical observations on the circulation. The validity of the technique is established (1) by comparison of the photoelectric records with simultaneous records obtained with transmission plethysmographs, (2) by comparison of the photoelectric records in instances of circulatory disturbances with independent directional confirmation by other methods in the literature.
Alrick B. Hertzman (Wed,) studied this question.