July 1920.] 



OGUBA:— GROWTH IN THICKNESS. 



101 



by other authors 1 . Some examples will be given in, the table VI (M, 

 maximum ; m, minimum ; L, average length in mm.). (Art. Jap., p. 

 (168), Table 12 2 , Fig. 8 3 ) 



Table VI 



Length of tracheids in Cryptomeria 





A (* 



r o. II) 





B (No. VIII) 





C X 



o. IX) 





X 



M 



m 



L 



X 



M 



m 



L 



X 



M 



m 



L 



1 



1.750 



0.550 



1.150 



1 



1.500 



0.525 



1.013 



4 



1.925 



0.400 



1.163 



3 



2.225 



0.650 



1.438 



5 



2.225 



0.900 



1.563 



10 



2 675 



0.675 



1.675 



13 



3.125 



0.900 



2.013 



10 



2.425 



1.150 



1.788 



20 



3.725 



0.775 



2.250 



23 



3.775 



1.025 



2.400 



20 



2.700 



1 150 



1.925 



40 



3.875 



0.S50 



2.363 



33 



3.925 



1.200 



2.563 



30 



2.675 



1.175 



1.925 



60 



4.250 



0.900 



2.575 



43 



4.225 



1,300 



2.763 



40 



2.S00 



1.200 



2.000 



so 



4.30O 



0.975 



2.638 



53 



4.325 



1.400 



2.863 



50 



3.275 



1.300 



2 2SS 



100 



4.550 



0.950 



2.750 



63 



4.425 



1.550 



2.983 



75 



3.775 



1.525 



2.650 



120 



4.800 



1.125 



2.963 



73 



4.600 



1.625 



3.113 



100 



3.825 



1.570 



2.69S 



140 



4.875 



1.100 



2.9S8 



83 



4.675 



1.575 



3.125 



125 



4.250 



1.625 



2.938 



160 



4.975 



1.175 



3.075 



93 



4.775 



1.725 



3.250 



150 



4.625 



1.575 



3.1C0 



180 



4.900 



1.075 



2.988 



103 



4.775 



1.750 



3.263 



175 



200 

 225 

 250 



4.700 

 4.575 

 4.525 

 4.500 



1.825 

 1.800 

 1.675 

 1.675 



3.263 



3.18S 

 3.100 

 3.088 



193 



4.925 



1.075 



3.000 



From the table we see that the length of tracheids increases with 

 age, and does not become constant as has been maintained by Sanio, 

 but gradually increases still further as noted by Bailey and Shepard. 

 Rate of increasement is greater at first, but gradually diminishes until 

 the length reaches the maximum at 150— 200th ring, beyond which it 

 begins to decrease very slowly. Such a tendency is also noticeable 

 in one case given by Bailey and Shepard. In order to examine the 



1. To be more correct, 'the mean' should be determined from a sufficiently 

 large number of measurements of the lengths of tracheids taken at random ; and the 

 best representative value is certainly 'the theoretical mode.' 



2. A, No. VI; B, No. II; C, No. I; D, No. II; E, No. VIII; F, No. IX; G, 

 No. X. 



2. Graphical illustration of Table 12. a, No. I; b, No. VIII; c, No. IX. 



