Cheeseman. — Age and Growth of the Kauri. 15 



It thus appears that the examination of twenty-nine sections gives 

 9-7 as the mean number of annual rings for each inch of radius. An 

 average based upon such a large number of examples cannot be very far 

 from the truth, and we may therefore proceed with some degree of 

 confidence to compare it with the estimates given by Kirk in the " Forest 

 Flora." 



Let us take first of all the gigantic tree at Mercury Bay, originally 

 reported and measured by Laslett (see " Timber and Timber - trees," 

 page 389), and subsequently mentioned by Kirk and others. I have 

 already quoted Kirk's opinion that its age " must be considerably over 

 four thousand years." The exact figures worked out on his own basis of 

 thirty annual rings per inch would be 4,320. But according to my average 

 of 9-7 rings per inch its age would not exceed 1,396 years. And I prefer 

 to take an estimate which, at any rate, is based upon the measurement of 

 a considerable number of examples, in place of accepting one which is little 

 more than a bare assumption. I consider that Kirk's figures are at least 

 three times the proper amount. Similarly, the specimen at Maunganui 

 Bluff, which is 22 ft. in diameter, and which according to Kirk has an age 

 of 3,960 years, under my views would not exceed 1,280 years. Kirk's 

 assertion that "the age of a tree 7ft. in diameter must be 1,260 years" 

 I have already combated on the ground that such an estimate is altogether 

 inconsistent with his very reasonable and correct view that a 5 ft. tree 

 would be 300 years old. Worked out on my average of 9-7, the age of the 

 7 ft. tree would be 407 years, and that of the 5 ft. tree 291 years. The 

 great majority of the kauri-trees that are now cut for sawing range from 

 3 ft. to 8ft., and the age of such trees, according to my calculations, and 

 subject only to a very narrow limit of error, would be 174 years for the 

 3 ft. tree and 465 years for the 8 ft. one. 



It may be objected that some weight ought to be attached to Kirk's 

 view that in trees of large size the increment of woody tissue formed each 

 year would progressively decline. But as long as the environment of the 

 tree is suitable, and the production of foliage is maintained, there is no 

 reason why that should take place. It is well known that a tree does not 

 cease growing when it arrives at maturity. Professor Marshall Ward says 

 that " as long as it is alive it continues to increase in bulk by the addition 

 of the annual layers developed by the cambium ; but when maturity is" 

 once passed each succeeding year produces a certain amount of deteriora- 

 tion at the centre." This deterioration ultimately leads to the tree becom- 

 ing hollow, but that does not prevent the cambium from forming additional 

 layers. Strasburger says (" Text-book of Botany," p. 239), " All that is 

 actually visible of a thousand-year-old oak is at most but a few years old. 

 The older parts are dead, and are either concealed within the tree, as the 

 pith and wood, or have been discarded like the primary cortex. The cells 

 of the original growing-point have alone remained the whole time alive. 

 They continue their growth and cell-division as long as the tree exists." It 

 is almost needless to say that in most parts of the world numerous examples 

 have been cited of hollow trees which are known to have continued their 

 growth for long periods. With respect to the kauri, in trees of large size 

 it is quite common to find the lower part of the trunk hollow. While 

 engaged in measuring the sections just tabulated I noticed several instances 

 the exact age of which I was unable to determine on account of decaying 

 wood or cavities in the centre. All these trunks had well-developed rings 

 of growth near the circumference. One in particular, which measured 



