298 IN THE GUIANA FOREST. 



irregular times it is always a young sap- 

 ling. 



Other signs of individuality are recognised by 

 the woodcutter, chemist, and tanner. Every timber 

 dealer knows that there are great differences among 

 woods, entirely apart from those produced by the 

 localities on which the trees grow. These are 

 popularly ascribed to the influence of the moon, 

 and rules are laid down for felling only at particular 

 stages of the planet's circuit. Every chemist and 

 pharmacist also recognises the differences in the 

 amount of the active ingredient in certain barks 

 and leaves, while the leather preparer is as well 

 acquainted with the varying amount of tannin in 

 his materials. All these differences are undoubtedly 

 due to the fact that some trees are better fitted 

 than others for the great struggle for life, and have 

 succeeded in secreting a larger quantity of the pro- 

 tective agent than their fellows. 



More obvious to the popular eye are the variega- 

 tions of ornamental foliage plants. Crotons are so 

 well known as to have received the name of " match- 

 me-not," from the impossibility of finding even two 

 leaves on the same shrub exactly alike. Several 

 species of Sida common roadside weeds are 

 equally conspicuous in the same way, and in the 

 forest variegation is by no means rare. As for 



