PROTECTION OF POLLEN. 123 



becoming curved and the flowers drooping towards the ground instead of facing 

 the sky as before. The same is true of the stalk of a Tulip (Tulipa), of 

 the long peduncles of BoronicuTn, of the flower -bearing stems of Asperula 

 arvensis, Astrantia major, Gardamine pratensis, Lychnis flus-jovis, and Primula 

 cortusoides. If you try to straighten the stalks again afterwards you run a risk 

 of breaking them. An interval of some hours elapses before this inflexibility 

 disappears and the tensions existing before the act of mechanical stimulation 

 are re-established and the stems become straight again. 



These different changes in the direction and position of petals, bracts, flower- 

 stalks and stems, which take place concomitantly with the alternations of night 

 and day, of storm and calm, cloud and sunshine, often imply a complete trans- 

 formation in the aspect of the vegetation within a very brief space of time. On 

 warm summer days, when the sky is clear and the air still, the green of the 

 meadows is sprinkled with the colours of innumerable open flowers. The 

 stellate, salver-shaped, and cup-shaped flowers and inflorescences of Anemones, 

 Ranunculuses, Potentillas, Gentians, and Composites are all wide open, so that 

 the upper brightly-coloured surfaces of their flowers are visible from a great 

 distance. Most of them are turned towards the sun, which enhances their 

 brilliancy; several of the flowers and inflorescences — as, for instance, the Rock- 

 rose (Helianthemum) — follow the sun, and face the south-east early in the 

 morning, the south at noon, and the south-west in the afternoon. Countless 

 flies, bees, and butterflies swarm and buzz round the flowers in the sunshine. 

 When the sun sets a cool breeze springs up, and there is a copious deposit of 

 dew on leaves and flowers. The insects withdraw to their homes to rest for 

 the night, and the flowers seem to fall asleep too. Petals fold up, heads of 

 flowers close, flowers and inflorescences bend towards the ground and exhibit 

 the inconspicuous outer surfaces of their floral envelopes to the onlooker. Whilst 

 the night lasts the meadow, drenched in dew, continues in a state of torpor, from 

 which it is awakened once more by the warmth imparted by the sun when it 

 rises next morning. A similar change of aspect occurs when a storm is brewing, 

 when the meadow is swept by wind and rain falls upon the flowering plants. 

 In this event also most flowers cover over or wrap up the parts liable to 

 destruction in time to prevent material damage being done to their pollen. 



Comparatively few among ordinary meadow plants appear to be in no way 

 affected by these alterations in external conditions. Some seem to be able to 

 dispense altogether with contrivances for protecting their pollen, for when once 

 the flowers have opened the pollen-cases are left free and uncovered even on 

 occasion of heavy showers. Thus, for example, in Plantago and Glohidaria the 

 anthers are borne on long filaments and project in both good and bad weather 

 out of the small flowers, which grow close together in spikes and capitula, and 

 it would seem as though their pollen were exposed to inevitable destruction 

 in case of wet. But closer inspection reveals that even these plants are not 

 destitute of apparatus for the protection of the pollen. To the anthers themselves 



