LETTER XIV. 



147 



Fig. 20. 



and say whether the circles be not singularly eccen- 

 tric ? Not only do we see the circles of different 

 years of very 

 different thick- 

 ness, but diffe- 

 rent sides — dif- 

 ferent portions 

 or segments of 

 the same circle, 

 widely different 

 in that respect. 

 Now, what I al- 

 lege is, that all 

 this is very ex- 

 actly propor- 

 tioned, as before 

 observed, to dif- 

 ferences in the 

 number and po- 

 sition of the 

 plants growing 

 on the tree, and 

 likewise to dif- 

 ferences in their 

 vigour, as influ- 

 enced by situa- 

 tion or expo- 

 sure, and by the 

 character of the seasons 



Fig. 21 



