56 VISCIDITY OF PLANTS. 
counted sixty-four small insects on one inflorescence of 
Lychnis viscosa. In other species the flower is viscid ; 
as, for instance, in the gooseberry, Linnea borealis, 
Plumbago Europea, &e. 
Polygonum amphibiwm 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 glandular hairs, but in others 
it is discharged by the ordinary cells of the surface. 
Kerner 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 
epidermis; while through the minute clefts thus made 
the milky juice quickly exuded, by which the ants 
were soon glued down. Kerner is even disposed to 
suggest that the nectaries which occur on certain 
leaves are a means of protection against the unwel- 
