132 VACCIN1UM, PRIMULACE&. [CHAP. 



bell, it inevitably comes in contact with one of the 

 anther processes, pr, which then acts like a lever, and 

 dislocates the whole chain of anther cells, when a 

 shower of pollen falls from the open anther cells on 

 to the head of the bee. 



Erica cinerea agrees very closely with E. tetralix. 

 In Erica (or Callund) vulgaris (the Common Heath), 

 on the contrary, where the flowers are, in their natural 

 position, more horizontal, the stamens and pistil 

 incline upwards, so that insects press their proboscis 

 under them, and in this manner the pollen is less 

 likely to be wasted, than if they were central as in E. 

 tetralix. In Erica vagans($b& Cornish Heath), E. carnea> 

 and E. ciliata, the anthers have no appendages. 



In the allied genus Vaccinium there is an arrange- 

 ment similar to that in Erica, but the anther cells 

 are closed, not by touching one another, but by 

 resting against the style, so that the style itself 

 closes the openings until the anthers are disturbed 

 by the proboscis of the bee. V. uliginosum is much 

 larger than V. Myrtillus, and consequently more 

 conspicuous ; V. Myrtillus, on the other hand, has the 

 compensating advantage of being richer in honey. 



The curious, brown-coloured, nearly leafless Mono- 

 tropa (Yellow Birds-nest), differs very much from the 

 rest of the order. 



PRIMULACE^:. 



This order is represented in Britain by eight genera : 

 Primula, Lysimachia, Trientalis, Glaux, Anagallis, 

 Centunculus, Samolus, and Hottonia. Cyclamen also 

 grows wild in some places, but is not a true native. 



I have already referred to the genus Primula in the 



