Standing Crops and Trophic Levels— -Blackburn 
45 
The correlation coefficients of Table 3 show 
that Z and M are independently related to C, 
and related to each other through their common 
association with C, but not otherwise. The re- 
gressions on C are 
Z = 1.8306 + 0.634 (C -1.2647) = 1.0288 
+ 0.634C ... (1) 
M = 0.7787 + 0.668 (C -1.2647) = -0.0661 
+ 0.668 C . . . (2) 
where 1.2647, 1.8306, and 0.7787 are means of 
C, Z, and M; the corresponding antilogarithms 
are 18.40 mg/m 2 of chlorophyll a, 67.70 ml/ 
10 3 m 3 of zooplankton, and 6.01 ml/10 3 m 3 of 
carnivorous micronekton. The 95% confidence 
limits of the regression ( slope ) coefficients 
in (1) and (2) are 0.639 ~t 0.211 (0.428 to 
0.850) and 0.663 ± 0.302 (0.361 to 0.965). 
The differences between such figures as 0.634 
and 0.639, 0.668 and 0.663, etc., in this paper 
arise from features of the regression methods 
used by Bartlett (1949). The fitted regressions 
and 95% confidence limits for the regression 
relationships are shown in Figures 3 and 4 as 
solid lines and dashed lines. 
Points within the confidence limits indicate 
the station-pairs at which the relationship be- 
tween C and Z (Fig. 3), or C and M (Fig. 4), 
is closest to the real relationship which exists be- 
tween the variables for all station-pairs. Figures 
3 and 4 show several points within the con- 
fidence regions, but only three of the station- 
pairs represented by these points are common 
to both regions. For analytical purposes it 
was thought permissible to consider additional 
station-pairs, which were represented by points 
Fig. 2. Station-pairs of Table 1, A and B (Northern Hemisphere Spring), showing the series AB-36, AB- 
11, and AB-8, discussed in text; approximate boundaries of high-chlorophyll and steady-state regions shown. 
