STRUCTURAL VARIATIONS IN HOMOLOGOUS CELLS 165 



TABLE XV 



Cell length and spiral angle in bamboo fibres 



* These angles are invariably larger than those defined by the m.e.p. for the same 

 species at the same length. This is because the m.e.p. measures the net orientation 

 (with a slight error due to the presence of the thin layers with a different orientation, 

 see p. 117) whereas dispersion about this direction contributes to the spread of the 

 arcs. 



This is perhaps more obvious in Fig. 58 where the line drawn through the 

 points (not calculated because the points are so few) represents the 

 relation 



L=750+200 cot d, 



where 6 is the average inclination to be expected in fibres of average 

 length L (in //). While the points are obviously far too few for any 

 reliance to be placed on such a quantitative relation, it is nevertheless 

 satisfactory that it takes the form already described for tracheids and 

 the constants are of the same order. 



