POLLINATION 231 



fruit and the proper nourishment of her children. When 

 the eggs are hatched the larvae feed upon the unripe 

 seeds for a time, but it is rare that more than a dozen or 

 two are destroyed in a pod, so that, after all, the plant 

 pays only a moderate commission for the service rendered. 

 An equally interesting partnership exists between the 

 Smyrna fig and the little insect, Blastophaga, an account 

 of which may be found in the Year Book of the Depart- 

 ment of Agriculture for 1900. In these cases the mutual 

 dependence is so complete that neither the plant nor the 

 animal could exist without the other. 



335. Protective Adaptations. Where plants have 

 adapted themselves to insect pollination it is, of course, 

 important to shut out intruders that would not make good 

 carriers. In general, small, creeping things like ants and 

 plant lice are not so efficient pollen bearers as winged 

 insects, and hence the various devices, such as hairs, sticky 

 glands, scales, and constrictions at the throat of the corolla, 

 by means of which their access to the pollen is prohibited. 

 To this class of adaptations belong the hairy filaments of 

 the spiderwort, the sticky ring about the peduncles of 

 the catchfly, the swollen lips of the snapdragon, the scales 

 or hairs in the throat of the hound's-tongue, the velvet 

 petals of the par- 

 tridge berry, etc. 



Of flowers that 

 are pollinated by 

 night moths, some 

 close during the day, 

 as the four-o'clock 

 and the evening 



primrose; and vice 456, 457. Protection of pollen in the thistle: 



versa, the morning. '" "" """"" ' ' * 



glory, dandelion, and 



day flower (Commelyna), unfold their beauties only to 

 the sun. For similar reasons, night-blooming flowers are 

 generally white or very light colored, and shed their fra- 



