LIFE HISTORIES OF FAMILIAR PLANTS 



a waxy covering. When grown in shady places 

 this protective covering will often disappear, for in 

 such situations there are no alternating heat and 

 moisture. 



It follows, therefore, that the bird's-eye 

 primrose would benefit by retaining its flower- 

 stalks in its mountain situation, since its flowers 

 would thus be held higher above the moist earth 

 and therefore kept drier ; and the fact that, not 

 only the flower-bearing stem, but also the calyx of 

 each individual flower, is well protected by the 

 waxy secretion, points to the conclusion that 

 the flowers take considerable risks of this kind. 

 Thus this seeming contradiction to my contention 

 regarding the primrose scarcely stands investi- 

 gation : it only tends to show that, as the bird's- 

 eye primrose experiences more varied conditions 

 of temperature than the common primrose, the 

 plant finds it better to retain its flower stem. 



The primrose provides its insect guests with a 

 widespread corolla, but that of the cowslip is not 

 so large and the flowers of the latter are pendulous, 

 and thus receive their visitors from below. These 

 differences may arise from the fact that each plant 

 caters for insects of a different class. It is sur- 

 prising how seldom insects appear to visit the 

 flowers of the primrose, yet Darwin has conclu- 

 sively shown that when the flowers are protected 

 from the visits of insects few or no seeds are 

 produced ; probably, therefore, their fertilisation 

 is largely effected by nocturnal insects. A mere 

 glance at the structure of the flower offers con- 



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