134 THE STRUCTURE OF FLOWERS. 



In many cases the capability of the flower to restrict 

 itself to its proper visitors, and at the same time to exclude 

 the ■wrong ones, is a common result of the differentiations 

 which have taken place. Thus, an elongated tube, as in 

 Evening Primrose, and in some species of Narcissus, etc., is 

 a direct result of and adaptation to the long proboscides of 

 Lepidoptera, and in proportion as the tube is elongated so 

 does it prevent the ingress of short-tongued insects, or of 

 those with short proboscides. 



Apart, however, from such and other general results of 

 adaptations, whereby flowers have become, for example, 

 irregular, and consequently their insect visitors are more 

 and more restricted in number, there are innumerable out- 

 growths of various kinds which act as special obstructions 

 to the entry of small insects which would not be able to 

 pollinate the flower. Thus, while many regular flowers, such 

 as Gentians, have developed horizontal hairs all round the 

 entrance to the tube of the corolla. Honeysuckle and Veronica 

 Chamcedrys, which are irregular and approached from one side 

 only, have developed them in the anterior side alone. In 

 Amaryllis belladonna Kemer describes 

 and figures (Fig. 41) a one-sided flap 

 growing out of the perianth, and so 

 folded as to famish a very small orifice 

 for the entrance of a proboscis. There 

 is no such growth on the anterior side, 

 but only on that one, the posterior, 

 which is probed by an insect. 



In Gentiana Bavarica there are 



Fig. 41. — Base of flower of .^mo- ,,,,., 



ryttis showing honey-protector tooth-like processes at the entrance of 



(after Eerner). _n j i i • i . t ,> t 



the tube, which remind one of the 

 appendages to the corolla of some of the Silenece. Monotropa 

 glabra and Daphne Blagayana agree in having a large circular 



