September, 1911.] 



215 



Edible Products. 



There is a very slight difference in 

 favour of the fertilized tree. However, 

 the difference observed was not always 

 in this direction ; and, considering the 

 general irregularity in the rate of 

 growth of roots, we are not at present 

 justified iu drawing any conclusions as 

 to the influence of fertilization on their 

 growth. 



As the dry season advances, the 

 growth of roots becomes slower, just as 

 was the case at San Ramon ; but the 

 checking is up to this time nothing like 

 so complete as was observed there. It 

 naturally occurs first where the soil is 

 thinnest. The row of trees under observ- 

 ation by A. Lejano is on shallower soil 

 than that of Cevallos. The average 

 daily growth of the roots of Lejano's 

 trees during the fall months was more 

 than 2 mm. ; but the average daily 

 growth of four roots from February 2 

 to February 16 was only 1*25 mm. The 

 average daily growth of two roots 

 measured by Cevallos from January 14 

 to February 18 was still 3 mm. 



The most rapid steady growth re- 

 ported for any roct was 108 mm. from 

 October 31 to November 26, covering 

 eight measurements, This was one of 

 T. Vibar's. During the first nineteen 

 days of February, his most active roots 

 grew 31 and 30 mm. respectively ; his 

 trees are intermediate between those of 

 Cevallos and Lejano. This relation 

 between the depth of the soil and the 

 ability of the tree to resist the evil in- 

 fluence of drought is very instructive. 



It is a good general rule, but naturally 

 not without exception, that the larger 

 the root the more rapid its growth. In 

 the saturated atmosphere of a buried 

 bottle, roots grow at about the same 

 rate as in the soil ; but the roots growing 

 in free air, where the new roots of 

 grown trees frequently emerge from the 

 trunk, grow very slowly until they 

 enter the ground. 



The Leafi 



My work on the growth of leaves at 

 San Ramon was very inadequate, be- 

 cause undertaken some time after the 

 beginning of a severe drought and con- 

 fined to young trees. As the growth of 

 the leaves is the most convenient cri- 

 terion by which the activity of a tree 

 can be determined at any one time, and 

 as it stands in a double direct relation to 

 the prospective productivity ot the tree, 

 we have here studied it with special 

 care and thoroughness. The following 

 tabulation of the determinations of the 

 growth of four of the trees measured by 

 Vibar will give a good idea of the 

 general rate. These trees are about ten 



years old and are coming into bearing. 

 The figures in each case represent milli- 

 meters of growth since the preceding 

 measurement- 

 Measurements can, of course, be made 

 only of the growth of the visible leaves. 

 The method employed was as follows : 

 A horizontal straight line of India ink is 

 drawn across the youngest leat as low 

 down as possible, and carried without 

 a break into the next youngest leaf. On 

 the lowest possible part of the latter 

 a similar mark is made, and carried 

 on to the next older. The same is 

 done on the lowest visible part of the 

 succeeding leaves. Where there is on 

 no growth, these marks, each drawn on 

 two leaves, will remain unbroken. This 

 would also happen if the two leaves 

 grew equally ; but in normal growth 

 the younger of any two visible leaves 

 usually grows the more rapidly. The 

 vertical distance between the two parts 

 of the broken line is then the difference 

 in growth. The break in the lowest 

 broken line is the growth of the oldest 

 growing leaf. The growth of the second 

 oldest growing leaf is found by adding 

 the break on the line at its base to the 

 break in the line below. And the 

 growth of each of the younger leaves is 

 found by adding the break in the line of 

 its base to the sum of the increments in 

 length ot the older leaves. Subsequent 

 determinations aie made by subtraction 

 without the use of new marks, except 

 when younger leaves make their 

 appearance. 



This general method is the only easy 

 and accurate one possible in working on 

 subjects of such size as the coconut 

 tree. In detail it can be modified as 

 convenience suggests: for instance, it is 

 sometimes simpler to draw a horizontal 

 line across several leaves. As the 

 growth of the leaves is entirely basal, 

 no error is introduced by marking one 

 point rather than another, so long as the 

 power to make accurate measurements 

 is not interfered with. 



Vibar's results showu in Table II show 

 the most rapid growth observed at any 

 time, 205 mm. in three days by tree D ; 

 but this rate was closely approached at 

 the same time by many trees. The 

 youngest leaf always grows the most 

 rapidly, or is sometimes equalled in rate 

 for a time by the next older. Independ- 

 ently of the environment the rate is 

 decidedly irregular, as is unmistakably 

 shown by comparing different leaves on 

 the same tree. It happens fairly fre- 

 quently that one leaf iucreases its rate 

 while another decreases it ; and this 

 change is not rarely in the opposite 



