Sept. 190*5.1 



215 



Sap* and Exudatxons. 



with, planters of an inventive frame of mind have convinced ;me that still better 

 results will accrue if a sound knowledge of the latex tubes has been obtained, and, 

 believing as I do that the permanent and most successful modes of cultivation and 

 latex extraction will be evolved by those in possession of such information, I am 

 going to run the risk of boring you to-day with a few details. 



WHERE DOES THE RUBBER COME FROM ? 



We will first consider the seeds of the Para rubber tree and see whether, in 

 their build, there is any clue to be obtained as to the source and nature of the 

 rubber after which we are all so eagerly searching. There are, under the micros- 

 cope here, some ten years old sections showing the components of Para rubber seeds. 

 I well remember how, in 1896, one out of every six students received one, and one 

 only, of those precious seedlings of Herea brasiliensis, which you are now distri 

 buting by the thousand to all parts of the tropical world. The sections under the 

 microscope, though made in London some ten years ago, are still in a good state of 

 preservation, but I must confess that had I been able to forecast events and to 

 imagine myself before you to-day, much better sections would have been submitted 

 to your critical scrutiny. In the sections before you can be seen the embryonic 

 parts of your giant trees, and in them the origin of the milk tubes can be traced 

 out in a satisfactory manner. There you can observe a mass of minute and more 

 or less regular boxes or cells, the material from which the future latex tubes arise ; 

 running irregularly throughout that beautiful network one can discern long 

 irregular stands of deeply-stained tissues, connected here and there with cross-bands 

 to form a much contorted ladder-like structure— that is the laticiferons system — a 

 system only in so far that it is irregularly connected at various points, and composed 

 of latex cells or tubes in all their stages. 



An examination under a higher power of the microscope will reveal to you 

 how the latex tubes arise and become filled with the globules of the different 

 substances which ultimately give you the rubber of commerce, for here and there 

 can be seen the breaking-down of the regular cells and the production of a single tube 

 by the disappearance of partition walls. [Blackboard demonstration followed here ] 

 This decomposition, essential for the production of the latex tubes in Para and Ceara 

 rubber trees, commences in the germinating seeds and continues until death, aud even 

 when the trees are to all appearances dead, they may, three years after throwing out 

 their last leaf, still maintain the milk tubes in a good condition and yield latex 

 of fair quality. This phenomenon adds one more to the perplexing points requir- 

 ing solution, and we are left to explain why latex tubes occur in only a small 

 number of plants, are never required by many species, and even when present 

 appear to have no vital functions to perform, and remain turgid and full of latex 

 when most other parts of the plant are dead. The abundance of latex in dead 

 stumps was mentioned at Kegalla, and since then you will have read of a similar 

 condition having been observed by Mr. Ridley at Singapore. 



HOW RUBBER FORMS IN THE BARK. 



The processes which you can see going on in the seedling take place in the 

 stem-bark of mature trees in exactly the same manner. What are perfectly normal 

 and regular cells in the bark to-day may begin to show perforations to-morrow and 

 within a few days or a week, a system of milk tubes may arise in an area which, had 

 it been tapped too early, would never have yielded a drop of latex. I leave it to you 

 to frame the moral to be drawn from a study of this curious development. The 

 formation of latex tubes from a series of single cells may be illustrated by knocking 

 out the cross-walls of an ordinary bamboo ; from a series of separate chambers a 

 single tube with the remnants of the cross-walls may be obtained. [Blackboard demon- 

 strations hei-e followed. 1 The main points I wish to impress upon you are, first, that the 



