THE LATEX AND HOW IT IS COAGULATED 129 



Darwin, for example, of how the existence of the common 

 clover depends on the old maids living in the country. The 

 explanation is as follows: The clover is only fertilized by the 

 humble-bee. The nests in the ground of the humble-bee are 

 ravaged by field-mice which greedily devour their winter 

 provision of honey. The humble-bees would perish and the 

 clover would not be fertilized but for the fact that there are 

 many old maids living in the country and these old maids keep 

 cats, which cats hunt the field-mice and keep them down. 

 Thus, through the existence of these unmarried ladies with 

 their domesticated pets, the bees are enabled to survive and 

 fulfil their task of carrying the pollen from one clover-plant to 

 the other and so fertilizing them. 



The plant food reserves in latex are very small and amount 

 at most to only about 2 per cent, of the volume. These are 

 entangled with other elements of no service as food reserves. 

 If latex is intended as a food reserve the tree has gone very 

 badly about its business and has shown none of the ability 

 which it has displayed in so many other directions. In the 

 endeavour to prove the theory that rubber latex is a food re- 

 serve, chemists have hunted for an enzyme, i.e., active ferment- 

 ing agent in the latex, which would render available the pro- 

 tein matters associated with the minute globules of caoutchouc. 

 This has not yet been found. In any case the amount of pro- 

 tein is very small. The essential hydrocarbon of crude rubber, 

 the rubber element proper, which forms 90 to 95 per cent, of 

 the solids in plantation rubber, appears a most unpromising 

 food material, and few have ever held out much hope for the 

 belief that it can be utilized by the tree. It is as if the tree 

 had locked up these stores in a strong room and had lost the 

 key. Only those with a knowledge of advanced chemistry 

 can understand the difficulties which the tree would have to 

 face to render such stores available. 



Dr Stevens has pointed out that the resins in trees must be 

 stores of plant food also if latex is. In such case the possi- 

 bility of drawing upon these resins appears most remote and 

 discredits the theory of plant food stores more than ever. 



There might be more warrant for considering the function 

 of latex to be the arming of the tree against insect attacks, 

 but in that case the tree has much over-loaded itself and wasted 



