PROTECTION BY THOICKETS OF HAIRS. 55 
In still more numerous species the access of ants 
and other creeping insects is prevented by the presence 
of spines or hairs, which constitute a veritable chevaua 
de frise. Often these hairs are placed on the flowers 
themselves, as in some verbenas and gentians. Some- 
times the whole plant is more or less hairy, and it 
will be observed that the hairs of plants have a great 
tendency to point downwards, which of course con- 
stitutes them a more efficacious barrier. 
In another class of cases access to the flowers is 
prevented by viscid secretions. Everyone who has any 
acquaintance with botany knows how many species 
bear the specific name of ‘Viscosa’ or ‘ Glutinosa.’ 
We have, for instance, Bartsia viscosa, Robinia viscosa, 
Linwm viscosum, Euphrasia viscosa, Silene viscosa, 
Dianthus viscidus, Senecio viscosus, Holostewm glu- 
tinosum, &c. Even those who have never opened a 
botanical work must have noticed how many plants are 
more or less sticky. Why is this? What do the plants 
gain by this peculiarity? The answer probably is, at 
any rate in most cases, that creeping insects are thus 
kept from the flowers. The viscid substance is found 
most frequently and abundantly on the peduncles im- 
mediately below the blossoms, or even on the blossoms 
themselves. In Epimedium alpinum, for instance, 
the leaves and lower parts of the stem are smooth, 
while the peduncles are covered with glandular, viscid 
hairs. The number of small insects which are limed 
and perish on such plants is very considerable. Kerner 
