''DEFENCE, NOT DEFIANCE. 143 



scious that the water was effectual protection enough 

 from all creeping insects ! 



Some plants prefer paying " black-mail " to such 

 predatory enemies, so that they may be left to their 

 lawful pursuits. They accordingly form nectaries 

 on their leaves, which secrete sweet fluids. Several 

 familiar plants, such as the Bean ( Vicia fabci), 

 some Vetches ( Vicia sepiuin and Vicia sativitni)^ 

 are illustrations of this endeavour to divert the 

 enemy, or bind him over to keep the peace, by 

 paying a special tribute. Kerner mentions, among 

 other familiar species, Inipatiens^ Ricintcs, VibiLvmim 

 tinus, and Vibiirmtm opiihis, in all of which the 

 leaves produce nectar for the entertainment of ants, 

 etc. In some instances the nectar is produced by 

 a special group of epidermal cells, transformed into 

 glandular tissue, as in Priums Laurocei^asics ; occa- 

 sionally it is secreted by special trichomes, or hair- 

 like organs, on the surface of the leaf or its stalk. 



Belt {The Naturalist in Nicaragua) has given 

 perhaps the most surprising instance yet known of 

 how a plant has adroitly converted what are gene- 

 rally a nuisance and pest into an extra means of 

 security, by affording food and lodgings to ants, 

 instead of killing them or driving them away : — 



" A species of Acacia, belonging to the section 

 Gtinimiferce, with bi-pinnate leaves, grows to a height 

 of 15 or 20 feet The branches and trunk are 

 covered with strong curved spines, set in pairs, from 



