JoHS. Schmidt 



117 



On the other hand, the very distinct gradation of average qualities 

 found in the ^ord populations seems to suggest that the surroundings 

 may be of importance, either directly or indirectly, but what factors here 

 come into play we cannot as yet determine. 



My view then, with regard to the nature of " races " in fishes, as 

 characterised by our population analyses, is briefly this: A fish "race" 



a = 119-M (±0-75) 



a = 108-06 {±0-69) 



Fig. 10. Zoarces viviparus, L. Number of vertebrae. Two population analyses from 

 Kjelds Nor, Langeland, Denmark (above), and Koskilde Fjord, Sealand, Denmark 

 (below). At both places the salinity is about 12 7oo- The boundary between the 

 populations indicated by a dotted line. 



is largely a statistical conception. It implies a mixing of different 

 genotypes, and the average values characterising the " race " arc pri- 

 marily dependent upon the quantitative proportion between these; 

 only secondarily on the environment. 



It should nevertheless be pointed out that we cannot expect to 

 arrive at any final decision before the results of the experimental 



