VARIATION 19 



That is, if measured and plotted the graph will approximate the normal 

 curve of variability (Chapter III). Continuous variations are either 

 heritable (combinations) or non-heritable (modifications) and, as was 

 stated above, the only certain method of determining the class in which a 



FIG. 3. Place-effects in common mustard (Brassica campestris) due to soil differences 



(herbarium specimens). 



given case may fall is the breeding test. Discontinuous variations are 

 essentially discrete differences whether they be large or small. They 

 are also either heritable or non-heritable and there is no correlation 

 between size and heritability. Thus the extremely large and small 



