277 



while the former averaged 2' 2 cm. and some of them were only 1*9 cm. 

 The volumes of two lots were found by placing them in graduated 

 cylinders, filling up to a known volume with sand, and then deducting 

 the volume of the sand. 100 fresh seeds from untapped trees weigh- 

 ing 4 11 '5 grams had a volume of 594 cubic centimetres while 100 seeds 

 from tapped trees weighing 353 grams had a volume of only 411 cc. 

 Thus, the volume of the latter is only about two-thirds that of the 

 former. But the decrease in volume is greater than the decrease in 

 weight, and from the figures last given the density of the " untapped " 

 seeds is 69, while the density of " tapped V seed is 86. As, however, 

 the seeds of tapped trees lose more weight on drying, this increased 

 density is probably due to an increased content of water. The method 

 of determining the density is only a rough one, no account being taken 

 of the air in the seed. 



The experiment, therefore, shows that the seeds from tapped trees 

 are smaller, weigh less per 1,000 seeds are actually denser, but lose 

 more weight in drying, than those from untapped trees. 



The Germination Tests. 



Turning now to the actual germination tests, the second part of 

 each table gives the percentage germination, and the time of germina- 

 tion of each of the lots. In lots 1 and 2 of both series several seeds 

 were dull brown, without the usual mottled outer layer. This layer is 

 formed last of all in the fruit and its absence may evidently be taken 

 as a sign that the seed has fallen before maturity, since none of these 

 brown seeds germinated. Unfortunately an unusually large proportion 

 of brown seed occurred in the, first hundred, and this spoils the per- 

 centage germination of the sample, though it does not affect the com- 

 parison to any extent. 



In series A seeds kept for four weeks did not germinate, and those 

 kept for three weeks showed only 3 per cent germination, beginning 

 after twenty-four days (they were kept for six weeks longer.) Practi- 

 cally the seeds from untapped trees were worthless if kept longer 

 than two weeks. In series B seeds kept for five weeks did not 

 germinate, but those kept for four weeks showed 28 per cent germina- 

 tion, beginning after seventeen days. Both in percentage, germina- 

 tion and time of germination the seeds from tapped trees are better 

 throughout. But it must be pointed out that these results deal 

 with germination only, and they give no information whatever as to 

 the quality of the trees which would result from the two sets of seeds. 

 Indeed, the earlier germination of series B, after the first week, might 

 indicate a precocity which is undesirable. An instance of this preco- 

 city is recorded in the Agricultural Bulletin of the Straits, &c, Vol. 

 VI., p. 176, where Mr. Ridley states that he was shown " a little lot of 

 trees of 3j years old, which had already commenced fruiting, and also 

 seedlings coming away nicely from the trees." The details given above 

 show that one or two factors have been overlooked in the published 

 estimates of the return to be obtained by extracting oil from Hevea 

 seed. Wright states (2nd edition, p. 155) : " The 500 old trees at 

 Henaratgoda and Peradeniya produce annually about 200,000 seeds, 

 equal approximately to one ton by weight." This assumes that 1,000 



