134 Chapters in Modern Botany chap- 



they are especially large and numerous on the bracts which 

 exhibit no movements. 



Schimper concludes that the theory of Belt and Delpino 

 is the only one which need be seriously considered. But 

 before it can be believed that the extra -floral nectaries 

 have arisen as adaptations to the protective ants, it must be 

 shown, as Schimper rightly observes : — 



(i) That the visits of the ants thus attracted afford so 

 much protection, that without them the plant would be at a 

 great disadvantage ; and 



(2) That the nectaries have not some other use in the 

 economy of the plant, to which they are primarily referable. 



By removing the extra-floral nectaries from various plants, 

 Schimper has convinced himself that they are unnecessary 

 and not demonstrably important for the wellbeing of the 

 plant. They are most abundant where there are most ants. 

 They certainly attract the ants, and these visitors sometimes, 

 but by no means always ward oft" leaf-cutters. The plants 

 which possess them may be worsted, but none the less they 

 had an advantage as far as it went. In short, Schimper 

 accepts the suggestion of Belt and Delpino. This con- 

 clusion has been further corroborated by W. Burck,^ who 

 finds that almost all plants with extra-floral nectaries or 

 food-bodies are truly myrmecophilous, and proves by direct 

 observation that the bodyguard of ants attracted by the 

 nectaries are of important service in driving off marauding 

 insects which spoil the foliage or perforate the corollas of 

 the flowers without effecting fertilisation. 



Domatia. — The homes which ants find inside the 

 Acacia's thorns, or within the hollow stems of Cecropia, 

 are not unique ; Dr. Lundstrom has described under the 

 title of domatia (meaning little homes) a large number of 

 shelters on plants which are tenanted by harmless little 

 1 Ann. Jardin Bot. Buitenzorg, x. (1891). 



