File:Apparatus used for recording spiracular valve movements - The Biological bulletin - Ca. 1825.jpg

Title: The Biological bulletin Identifier: biologicalbullet119mari Year: [1] (s) Authors: Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mass. ). Annual report 1907/08-1952; Lillie, Frank Rattray, 1870-1947; Moore, Carl Richard, 1892-; Redfield, Alfred Clarence, 1890-1983 Subjects: Biology; Zoology; Biology; Marine Biology Publisher: Woods Hole, Mass. : Marine Biological Laboratory Contributing Library: MBLWHOI Library Digitizing Sponsor: MBLWHOI Library

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Text Appearing Before Image: SPIRACLES IN CYCLICAL RESPIRATION 499

Text Appearing After Image: diomber FIGURE 3. Apparatus used for recording spiracular valve movements. The observation chamber shown is of the sort also employed in studies with intubated pupae. For further details see text. continuous feed kymograph (Fig. 3). The tracings of the ink-writing pen provided a record of the movements of the spiracular valve, each deflection on the record representing a valve movement. The ordinate of the trace shows the width of valve opening in arbitrary units, while the abscissa denotes the duration of the opening. Directly beneath the record of valve movements the time was recorded by an ink-writing timer. In most of the experiments spiracular behavior was viewed through a 20-cc. glass chamber in which the insect was held secure in a plasticene support, or in a 250-cc. lucite chamber with a flat surface for optical convenience. Air and gas mixtures were flushed through the chamber as desired. The rate of gas flow varied from 25 to about 500 cc./min. in different experiments and appeared to have no effect on the phenomena under investigation. The time required to change the atmosphere in the small chamber was rarely longer than 10 seconds, but for the large chamber it took about two minutes. Gas mixtures were either pre-mixed in pressure cylinders or made up by propor- tional flow. All mixtures were analyzed periodically. A. EXPERIMENTS WITH INTACT PUPAE 1. Normal behavior of spiracles Figure 4 is a portion of a typical record of the activity of the third abdominal spiracle of a Cecropia pupa over a period of four hours. A consistent pattern of

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