551(1 5 3 13 T8I 5935710159 MTKl k? 1)5 7 1*5 ?I5!7 1615? mnji 5 9 



Boiiy Lfflt''- 



Figure 4, --Length frequency by season with noted modes. 



Bi (1948)- 

 .... (B) 



a2A2 (1950)- 



'C< (1949)- 



-D2 (1950) 



-A"b" (1951)- 



-»-B, 



(1952) (C) 



These relationships can be established. 

 However, the same difficulty exists with re- 

 gard to (c) as for (A). We shall investigate 

 further to try to find out whether the diffi- 

 culties pointed out for assumptions (A) and (C) 

 are of a nature such as to overthrow these 

 assumptions completely or whether they are 

 of such a nature that a reasonable explanation 

 can be given for them provided certain condi- 

 tions are fulfilled. For convenience in the 

 explanation the problems will be divided into 



two: (a) ajA^ »-A'b' and a2A2 ^-A"b" 



(b) A'b' *- B2 and A"b" fc-Bs 



On problenn (a): 



A'b' is thought to be compounded of two 

 groups shown by A' and b'. In the same 

 manner ajAj can hardly be thought, in view of 

 the form, to be a single mode, and it is 



probably valid to think of it as being compounded 

 of two groups shown by aj and Aj. If we take it 

 that this assumption is correct, ajAj and A'b' 

 will be understood to have no particular incon- 

 sistent relationship in their essential 

 composition. The same sort of assumption is 

 established with regard to the relationship be- 

 tween a2A2 and A"b". The point that needs to 

 be noticed here in the comparison between A'b' 

 and A"b" is that whereas the displacement be- 

 tween A' and b' in the former is small, that 

 between A" and b" in the latter is relatively 

 great. However, this sort of difference is not 

 fundamentally in opposition to the point that 

 they are made up of two groups as stated above. 

 Consequently, it can probably be thought that 

 the elements which prevent the rational estab- 

 lishment of t h e assumptions ajAj ^A'b' 



^•A"b" arise chiefly from 



and a2A2 • 



differences in the relative abundance between 



the two different group*. 



Table 2 shows the relative abundance 

 between the two groups mentioned above. As 

 far as the division into two groups is concerned, 

 there is no particular problem in the case of 



28 



