. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 256 REPORTS FROM THE MBL GENERAL SCIENTIFIC MEETINGS end of the 6-s period. This was repeated at 1-min intervals 30 times daily on 3 successive days. On the fourth day, the animals were tested with light alone. We videotaped the movements of the animals for 1 mm in the orange light, measured the lengths of the animals at l-s intervals and computed the length differences between the start and end of successive 3-s intervals. Lengths were measured on the monitor to an accuracy of about mm; this agrees with the value of
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 256 REPORTS FROM THE MBL GENERAL SCIENTIFIC MEETINGS end of the 6-s period. This was repeated at 1-min intervals 30 times daily on 3 successive days. On the fourth day, the animals were tested with light alone. We videotaped the movements of the animals for 1 mm in the orange light, measured the lengths of the animals at l-s intervals and computed the length differences between the start and end of successive 3-s intervals. Lengths were measured on the monitor to an accuracy of about mm; this agrees with the value of mm for the standard error in the sense that two standard errors, or mm, include almost all the actual data. Thus changes larger than mm (so that t > 2; /; < ) are truly changes and not just measurement variations. Typical results (Fig. 1. top) show many periods of increase and decrease in length for six animals living in aerated natural seawater. Multiples of 3 mm were added to the data for the various animals to separate the curves from each other. Figure 1 (middle) presents the results tor five animals living in aerated natural seawater containing 1 ppm of lead acetate. This ficure also shows periods of increasing and decreasing length. The range of values differs from that in the top figure because different multiples of 3 mm were added. The test data were then studied to determine whether a suffi- cient number of animals actually manifested a length extension so as to account for the missing 30% of contractors. For eight control animals, of 132 length differences mea- sured, 46 were extensions equal to or greater than the criterion of two standard errors, or about mm; this is close enough to the observed missing 30% contraction rate to explain the apparent failure of that percentage of the animals to manifest contractions. This suggests that close to 100% of the animals were successfully trained. When previous data for another group of 23 con
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
