FRANKINCENSE AND MYRRH 



WHEN we come in the sunshine upon a patch 

 of mown grass with a good proportion of 

 Sweet Vernal, we experience, with all normally 

 constituted mankind, a great sensory satisfaction. 

 The fragrance is delicate, complex, and restful; for 

 the moment all is right with the world. But why 

 it should be so, it is difficult to tell. The odor- 

 iferous substances in plants are usually ethereal 

 oils and -resins, by-products or end-products of 

 certain vital chemical processes. Little is known 

 of their physiological significance in the economy 

 of the plant; most of them rank as waste-products. 

 But should one of them turn out to be very attractive 

 to the olfactory sense of welcome insect-visitors, 

 such as bees, or very repellent to voracious enemies, 

 such as snails, then it will tend to acquire survival- 

 value, and, other things equal, to grow in strength. 

 We have to think of all these new departures for 

 they must all have had their beginnings as like 

 tendrils probing the unknown. If they get no 

 encouragement they come to little, except in so 

 far as they are the necessary corollaries of indis- 

 pensable antecedent processes; if they find a 

 support they grow strong. Thus some of the 



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