66 VISCIDITY OF PLANTS. 



counted six*-.y-foiir small insects on one inflorescence of 

 Lychnis viscosa. In other species the flower is viscid ; 

 as, for instance, in the gooseberry, Linncea burealia, 

 Plumbago Europcea, &c. 



Polygonum amphibium is a very interesting 

 ease. The small rosy flowers are richly supplied with 

 honey ; but from the structure of the flower, it would 

 not be fertilised by creeping insects. As its name 

 indicates, this plant grows sometimes on land, some- 

 times in water. Those individuals, however, which 

 grow on dry land are covered by innumerable glan- 

 dular viscid hairs, which constitute an effectual pro- 

 tection. On the other hand, the individuals which 

 grow in water are protected by their situation. To 

 them the glandular hairs would be useless, and in fact 

 on such specimens they are not developed. 



In most of the cases hitherto mentioned the viscid 

 substance is secreted by glandiJar hairs, but in others 

 it is discharged by the ordinary cells of the surface. 

 Kemer is even of opinion that the milky juice of 

 certain plants — for instance, of some species of Lactuca 

 (lettuce) — answers the same purpose. He placed 

 several kinds of ants on these plants, and was surprised 

 to find that their sharp claws cut through the delicate 

 epidemais ; while through the minute clefts thus made 

 the milky juice quickly exuded, by which the ants 

 were soon glued down. Kemer is even disposed to 

 suggest that the nectaries which occur on certain 

 leaves are a means of protection against the unwel« 



