. The Biological bulletin. Biology; Zoology; Marine biology. MOTOR REACTIONS OF THE FRESH-WATER SPONGE. I63 the stimulus was mild, there would be an immediate contraction followed by a slower more general contraction. In this case the chimney would remain contracted for a few minutes and then expand much more slowly than it had contracted. In the second instance, all of the contractile cells probably were directly stimulated by the electrical current, while in the first case it is probable that only those where the electrodes were applied were directly stimulated, the gradual contraction being
. The Biological bulletin. Biology; Zoology; Marine biology. MOTOR REACTIONS OF THE FRESH-WATER SPONGE. I63 the stimulus was mild, there would be an immediate contraction followed by a slower more general contraction. In this case the chimney would remain contracted for a few minutes and then expand much more slowly than it had contracted. In the second instance, all of the contractile cells probably were directly stimulated by the electrical current, while in the first case it is probable that only those where the electrodes were applied were directly stimulated, the gradual contraction being the result of transmission of the stimulus from one cell to the next. In one instance, following a very weak stimulation for thirty seconds, it was possible to keep an accurate measurement of the time required for contraction and relaxation of the sphincter at the mouth of the osculum. No check was made on the general contraction or relaxation of the chimney. That the contraction was slower than the relaxation is shown by the following graph. The temperature of the water was about 270 Min. 5 10 15 20 25 30 35 40 45 50 55 60 65 70 Fig. 5. Graph showing the rate of contraction and of relaxation of the sphincter at the mouth of an osculum following a weak Faradic stimulation. The abscissa represents the intervals of time in minutes and the ordinate the diameters of the opening in millimeters. Transmission of Stimuli. It has already been pointed out that, apparently, very little transmission from one part of the body to another resulted from the application of the various types of stimuli used in these experiments. To determine if there was any transmission at all,. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Lillie, Frank Rattray, 1870-1947; Moore, Carl Richard, 1892-; Redfield, Alfred Clarence, 1890-;
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectb, booksubjectzoology
