. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 376 MEREDITH L. JONES was niicra (one standard error ~ micra) and that of the down-river forms was micra (one standard error -- micra). Utilizing the "Student" t test, it was found that there was, indeed, a significant difference between the mean canal diameters of the two forms (£ — ). This also can be interpreted as the difference between the two means being times the standard error of this difference. The results above, however, may not be so straightforward as they might seem. If
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 376 MEREDITH L. JONES was niicra (one standard error ~ micra) and that of the down-river forms was micra (one standard error -- micra). Utilizing the "Student" t test, it was found that there was, indeed, a significant difference between the mean canal diameters of the two forms (£ — ). This also can be interpreted as the difference between the two means being times the standard error of this difference. The results above, however, may not be so straightforward as they might seem. If the mean canal diameter (±2 standard errors) of each nephridium examined is plotted against salinity (Fig. 13), it is seen that there is a rather large spread of the data derived from the up-river forms. Indeed, the results from three of the up-river worms (S-2, 49C and RB) indicate that there is a real difference be- tween and among the diameters of the nephridial canal in the same animal, and. 10 15 20 25 30 35 40 45 Micrometer units (I unit = l. 50 55 60 65 70 FIGURE 12. Frequency polygons showing the difference in nephridial canal diameter between the up-river forms of Nereis limnicola (based on 14 nephridia from six specimens) and the down-river forms (based on ten nephridia from four specimens). two specimens (S-2 and 49E) have nephridial canals whose diameters are not significantly different from at least some of those from the down-river locality. In addition to observations of the nephridia of worms sacrificed directly from the salinities in which they were collected, examinations were made of the nephridia of two cross-adapted worms. In the case of specimen S-l (originally up-river), the adaptation was from sea water to 118% sea water and of S-4 (originally down-river), from 81% sea water to sea water. The general aspect of the nephridia of both S-l (Figs. 14 and 15) and S-4 (Figs. 16 and 17) is strikingly similar to the nephridia of the up-river popu
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
