The physiological function of the book lungs of Arachnids has not received a great deal of attention. No attempt has been made to investigate their respiratory function, and what references exist deal with the question of respiratory movements. Treviranus (1814) stated that there are no respiratory movements in scorpions. Muller (1828) described an extension of the lung membrane over the stigma, forming a valve-like structure, but he recorded no respiratory movements. Blanchard (1851) observed rhythmical movements of the dorsal wall of the lung sacs, causing the opening and shutting of the stigmata. Plateau (1887), on the other hand, using methods of graphical recording, failed to discover any movement of the respiratory apparatus. The respiratory movement of the abdominal plates bearing the book gills in Limulus polyphemus are unquestionable, and was shown by Hyde (1894) to be under nervous control.
The structures described in text-books as the respiratory organs of...
