468 ^^^ Philippine Journal of Science isu 



north and south and the second east and west; the average of 

 the 2 measurements was taken as the correct reading. The 

 second measurements were made by us in March, 1914, with 

 the assistance of F. W. Foxworthy and D. D. Wood. These 

 measurements were all made with a steel tape. In some few 

 instances it was not possible to locate the exact point at which 

 the first measurement was taken, but where this was the case 

 and where there was sufficient irregularity in the bole of the 

 tree to make the data unreliable the measurement was discarded. 



In the first series of measurements the data collected are known 

 to be accurate for the year in question. There are presented 

 in this paper climatic data for the period covered by the meas- 

 urements, and from a comparison of these data with those for 

 the Islands as a whole for the last ten years it appears that the 

 year 1913 to 1914 does not depart markedly from the normal 

 with respect to climatic factors. The greatest number of meas- 

 urements for any one species were those for Parashorea plicata 

 on Mount Maquiling. A second yearly record of the growth 

 of this species was taken in January, 1915. According to these 

 figures the age of a tree 70 centimeters in diameter differed 

 from the age calculated in this paper by only 1.4 per cent. This 

 indicates that the rates of growth shown by the measurements 

 in the first series are very close to the average yearly rates of 

 the species measured. In the second series of measurements 

 the period covered is so long that any inaccuracies arising from 

 the periodic variations of climatic factors may be considered 

 negligible. 



The original figures as collected were in the form of meas- 

 urements of size and growth in terms of centimeters of girth. 

 The first steps in the reduction of these figures to usable form 

 were their reduction to diameter figures, with the growth re- 

 duced to a period of one year, on the assumption that the girth 

 was a circle. These figures were then grouped by species 

 and diameter classes of 5 or 10 centimeters, and tables were 

 prepared showing the growth of each tree of any one species 

 or group of species for the period of one year and the total and 

 average growth of all the trees in each diameter class. When- 

 ever sufficient data for one species were at hand, a table for 

 that species, independent of all others, was prepared. In most 

 instances, however, this was not possible with the figures from 

 Bataan, and in order to group the data into usable form the 

 following classification of species was adopted : All of the species 

 under consideration were grouped into 4 classes. Class I in- 

 cludes all species, such as the dipterocarps, which at maturity 



