November, 1908.J 



415 



Swps and Exudations* 



do not produce good seed ; and he 

 supports this view by figures obtained 

 iu Annam. Thus, trees, 7 years old, 

 produce seed weighing 381 grammes per 

 100 ; trees 8 and 9 years old, 493 grammes 

 per 100; and trees 10 years old, 530 

 grammes per 100. Since seed from 

 Ceylon trees, twenty to thirty years 

 old, weighs less than this, we must, 

 if this view is correct, expect a 

 maximum weight per one hundred seed 

 between the ages of ten and twenty; and 

 the result is at variance with Mr. Ridley's 

 view that the early fruiting gives 

 large seed getting a little smaller in 

 later years. But it must be objected 

 that results in this matter can only 

 be obtained by weighing: the seed from 

 the same group of trees for several 

 years, the trees meanwhile remaining 

 untapped- The Peradeniya results 

 showed that trees 26 years old produced 

 seed weighing 409 grammes per 100 

 seed ; for years later, the same trees, 

 now tapped, produced seed weighing 

 354 grammes per 100, while in the same 

 years, untapped trees 20 years old, 

 produced seed weighing 412 grammes 

 per 100. Are we to suppose that the 

 weight per 100 seed is constant between 

 the ages of twenty and twenty-six, 

 but drops 12h % between twenty-six and 

 thirty? It is quite possible that the 

 weight of the seed varies with the age of 

 the tree, but this'can only be proved by 

 Aveighing the produce of one tree, or a 

 small group of trees, for a number of 

 years: and the experiment will prove 

 nothing if the trees are tapped. 



Mr. Vernet justifies his rejection of 

 seeds weighing less than five grammes 

 each by an experiment which shows 

 that their germination is only 56 %, 

 while that of seeds weighing over five 

 grammes is 91%. In contrast to this, 

 the germination of one-hundred Ceylon 

 seeds weighing 315 grammes was 93 % 

 in one case, and 90 % in another. It 

 would certainly not be expected that 

 the germinative capacity of fresh seeds 

 would be governed by the weight, un- 

 less the smaller weight indicates that 

 the kernel has lor some reason not de- 

 veloped properly. But on this point 

 no information is given. Mr. Vernet's 

 results are without parallel in Ceylon. 

 The Annam maximum weight per one- 

 hundred seeds is 630 grammes, and seeds 

 weighing less than five grammes each 

 show a small percentage germination. 

 The Ceylon maximum per hundred seeds 

 is 431 grammes, so that we ought on 

 this principle to have a low percentage 

 germination with seeds weighing less 

 than three-fourth grammes. Instead, we 

 obtain 93 % germination from one-hun- 

 dred seeds which weighed 345 grammes. 



A further experiment by Mr. Vernet is 

 taken to prove that the amount of water 

 in the kernel is proportional to the 

 yield of rubber by the tree. The yield 

 of rubber is not stated, but with three 

 series of trees in increasing order of 

 yield, the percentages of water in the 

 kernels were twenty-four, forty-five 

 and sixty-three respectively. The trees 

 were unfortunately of different ages. 

 Corresponding figures for Ceylon are not 

 available, but it has been shown that the 

 small seeds from the tapped trees lose a 

 greater percentage of their weight in 

 drying than the larger seeds from un- 

 tapped trees. We may provisionally 

 conclude therefore that the seeds from 

 tapped trees contain a greater percent- 

 age of water than seeds from untapped 

 trees; and Mr. Vernet's result confirms 

 this if taken to mean that the greater 

 percentage of water is a consequence of 

 the removal of the latex or bark. 



An experiment showing the variation 

 in the time of germination of one-hundred 

 seeds gives another instance of wide 

 departure from Ceylon results. The time 

 between the germination of the first 

 and last seeds was twenty-six days, and 

 fourteen days have elapsed before 50 % 

 had germinated. In our experience, 

 80 % germinate without the first three 

 days of germination, and, with fresh 

 seed, all have germinated within seven 

 days. A series of germinations extend- 

 ing over twent y-six days would be con- 

 sidered to prove that the sample was a 

 mixed one, i.e., consisting of seeds which 

 had been gathered at different times. 



Mr. Vernet's remaining experiments 

 deal with methods of preserving the ger- 

 minative capacity of the seeds. Seeds 

 werekept 'in a closed box for periods up to 

 forty days. Those planted after having 

 been thus kept for thirty-five days gave 

 95 % germination, and those kept for 

 forty days gave 80 %. The number of 

 seeds tested was only twenty in the first 

 case, and ten in the second. A similar 

 experiment in which the seeds were pre- 

 served in dry charcoal gave only 25 % 

 germination after twenty-five days, and 

 20 % after forty days. Mr. Vernet de- 

 precates the use of moist charcoal because 

 the seeds germinate in the charcoal, and 

 the roots and stems are liable to be dis- 

 torted or broken. 



There is still need of considerable ex- 

 tension of experiments of this nature. The 

 results at present recorded show such 

 wide differences that no general conclu- 

 sions can be drawn from them. It would 

 be interesting to have similar figures from 

 the Federated Malay States, Singapore, 

 andother countries in which Hevea brasi- 

 liensis is grown. T. PETCH, 



Govt. Mycologist, 



