176 



Plant Tissue Culture 



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ro 



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o e 



20:0 



1980.2 100: 1 - 



Osmotic values in atmospheres 



0,45 1,5 4.5 



1_> 



19.4: 0.6 30: 1 



>- 182 10:1 



15:5 3:1 - 



FlG. 47. An isopleth diagram (three-dimensional graph) show- 

 ing the approximate average increment rates (indicated by isopleth 

 lines) obtained when tomato roots were grown in solutions in which 

 the concentrations of sucrose and of sodium chloride were simul- 

 taneously varied in a regular way so as to obtain a graded series of 

 ratios (indicated on the ordinates) and a simultaneous graded series 

 of osmotic values (indicated on the abscissae). This type of dia- 

 gram, which may also be built into the form of a solid graph like 

 a relief map, is extremely useful when it is desired to record the 

 effects of the interaction of two simultaneous variables. (From 

 White, P. R. 1942. Plant Physiol. 17 : 159, fig. 5, 37.) 



