. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. RESPONSES TO MAGNETIC STRENGTH CHANGES 220 was determined as deviation from the average path for all controls in the series (method B). Maximum variance again occurs at gauss with a value of °. Minimum variance, °, occurs at gauss. The ratio of these variances, or F, is (P. 0 LOG FIELD STRENGTH FIGURE 4. The variances obtained for responses to the reversed fields as computed from the data illustrated in Figure 3. The solid curve shows variances computed from 6 mean monthly values, and the bro
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. RESPONSES TO MAGNETIC STRENGTH CHANGES 220 was determined as deviation from the average path for all controls in the series (method B). Maximum variance again occurs at gauss with a value of °. Minimum variance, °, occurs at gauss. The ratio of these variances, or F, is (P. 0 LOG FIELD STRENGTH FIGURE 4. The variances obtained for responses to the reversed fields as computed from the data illustrated in Figure 3. The solid curve shows variances computed from 6 mean monthly values, and the broken curve, from three mean annual ones. The vertical dashed line indicates the strength of the earth's horizontal component. DISCUSSION Mud-snails initially directed geographic southward display a characteristic mean turning tendency away from this southward path; when directed geographic north, a different mean turning tendency is evident (Brown, Webb and Barnwell, 1964). It was the intent of this investigation to learn at what strength of an abruptly re- versed horizontal magnetic vector the snails would be induced to alter to the great- est degree their characteristic "south"-turning tendency. It is significant of itself that despite the fact that the conditions of the experi- ment differed over the three summers of study in symmetry of background, in state of the ambient electrostatic field, and in time of day, one relatively uniform result was found. This was that the maximum tendency to alter direction in response to the experimentally reversed horizontal magnetic field appeared to occur when the strength of the reversed field was that one closest in strength to the natural terrestrial one. On the other hand, it is unfortunate that the variety of conditions used for experiments renders it impossible at this time to reach any similarly well sup- ported conclusion as to why the response should have been for three out of the six months a counterclockwise response
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
