LIFE HISTORIES OF FAMILIAR PLANTS 



So, covered with pollen, they ascend the central 

 axis preparatory to leaving the bloom. The 

 barrier bristles now no longer stop the way, for 

 the plant has no further use for the insects' com- 

 pany ; they have done their work, and received 

 their due payment, therefore they are now al- 

 lowed their liberty. So on reaching the purple 

 club the insect pushes off it into space. The 

 air, together with the insect's flight, refreshes it 

 wonderfully, so much so that probably before it 

 has travelled many yards it becomes fascinated 

 by a most charming purple club standing out 

 fresh and cool against an enfolding pale-green 

 sheath. Thus it is enticed once more into another 

 arum bloom to be prisoner for a few days ; and 

 while there, it will have plenty of time to clean 

 its pollen-laden limbs and rub the grains about 

 the sticky stigmas of the flowers within. Thus 

 the whole process is once more repeated. 



In Fig. 30 (Plate 20) is shown a magnified view 

 of the wings of a midge taken from an arum that 

 had yet to shed its pollen, and the numerous tiny 

 grains (brought from a previous bloom) adhering 

 to its wings should be observed. Also, it should 

 be remembered that only one of these microscopic 

 grains is needed on the stigma to effect the fertilis- 

 ation of the ovary of each female flower. 



Before our present-day knowledge of the re- 

 lationship between insects and flowers, the fact 

 that the male flowers are arranged above the 

 female and shower down pollen upon them would 

 have been held sufficient to show how perfectly 



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