HISTORICAL SKETCH 



xix 



atmosphere is an important factor bearing upon the intensity 

 of floral odoiu"s. In the hot dry weather of summer many 

 flowers lose a large share of their usual fragrance, and in 

 walking through a Trilderness of sweet-smelling plants we 

 find little trace of their odour, but if a heavy shower follow, 

 the air soon becomes impregnated with a bouquet of delicate 

 balsamic essences, clearly demonstrating what an important 

 bearing the addition of moisture to the air has upon the 

 odoriferous organs of plants. 



Some flowers emit their strongest perfume at early da^^ii, 

 and are C[uite scentless dm^ing the day, others breathe their 

 sweetness during the evening, or on the dews of the night. 

 These were daintily designated by Linnaeus the Flore frisfes^ 

 or melancholy flowers, because they are generally of a dull 

 and dismal coloin^, and seemingly require the brightness of 

 daylight to impart to their petals the brilliancy of which they 

 are void ; these are the flowers 



^ That keep 

 Their odours to themselves all day, 

 But when the sunlight dies away, 

 Let the delicious fragrance out 

 To every breeze that roams about.' — Friend. 



Or as a tasteful American poetess puts it : — 



* All night incense's sweetest fragrance 

 Rises from those perfumed bowers, 

 Through the moonlight's silver radiance 



From the yellow Jasmine flowers.' — Mutrhead. 



Every plant has its special insect ^asitants, which are 

 necessary to its economy, and without whose aid its seeds 

 would either remain unfruitful, or would be fructified in 

 an inferior manner. Hence the plants suited to these night- 

 fliers are endowed with the singular property of giving out 



