CHAPTER IV 



Rate of growth — Point of measurement — Sir R. Christison's view 

 — Objections — Instances — Measurements of trees of known 

 age — Increase at fixed points and at stated periods — 

 Examples — Dr. Christison's and Dr. Beddoe's measurements 

 — Mr. Bowman's method— Trephine — Objections — Traditional 

 accounts — Fallacies — Rate of growth in old trees — Periods of 

 rest and growth. 



Before considering the rate of growth, it is 

 necessary to fix on the point of measurement. 

 Christison ^ thought that the lowest level is the 

 only suitable spot for comparative measurement, 

 ' because the annual orowth of the rino-s of wood 

 increase in width in a progressive ratio upwards, 

 owino- to the o-radual increase of the swellinof under 

 the division of the trunk into its lowest limbs.' 

 This is in part, but not altogether true. The 

 swelling is due mainly to the welding of the lower 

 shoots together, and not to the division of the 

 trunk, which is quite another thing. He says, 

 further, that the ground-line is fortunately the right 

 place, ' for most aged yews ' have their trunks so 



^ Trans. Bot. Soc. Edin., 1S79. 



