CHAPTER XVII. 



TIIK RF.L. \TIONS OF ANTS TO VASCULAR PLANTS. 

 " Plantas itaqtn- nonint formic;e." Michael Gehlerus, 1610. 



" Die Krgriindung der intcressanten Gemeinschaft zwischen Pflanzen und 

 Ameisen wurde bislier als ein rein botanisches Problem aufgefasst. Aber gerade 

 hierin liegt \\enn mir ein Urteil in dieser Frage zugestanden werden sollte 

 die Ursache der geringen Erfolge, um nicht zu sagen der Misserfolge. Man war 

 sti't> all/u.sflir geneigt, die Anpassungsfahigkeit der Pflanzen an plutzlich ein- 

 treteiuic, sie beruhrende Verhaltnisse, als erheblich hinzustellen, umgekehrt aber 

 glaubte man diejenige von lebenden Wesen mit so achtungsgebietender Begabung, 

 \vie solche den Ameisen eigen ist, iibergehen zu miissen ; der Instinkt dieser 

 findigen Tiere tauschte eben iiber den nur hochst schwerfallig arbeitenden An- 

 passungsmechanistnus der Pflanze hinweg." - Rettig, " Ameisenpflanzen und 

 Prlanzenameisen," 1904. 



The hypothesis of intimate mutualistic relations between ants and 

 the higher plants is one of those fascinating constructions in which 

 certain gifted and imaginative botanists have rivalled the inventors of 

 the mimicry hypothesis in the zoological field. Both of these construc- 

 tions have been treated as facts of the utmost value in supporting a 

 still more general hypothesis that of natural selection, and both, after 

 having been carried to extremes by their respective adherents, are now 

 facing the reaction that is overtaking Neodarwinism. Authors like 

 Fritz M iiller, Schimper, Huth, Delpino, Beccari and Heim have mar- 

 shalled a formidable array of observations in favor of the view that 

 many plants develop elaborate structures to be used as lodgings by 

 certain pugnacious ants or even furnish these insects with exquisite 

 food substances, and in return for these services are protected by their 

 tenants from the leaf-cutting ants or from other leaf-destroying ani- 

 mals. These observations are now being subjected to critical revision 

 by authors like Rettig and H. von Ihering, whose attitude towards the 

 whole subject is avowedly skeptical and reactionary. It behooves us 

 therefore to examine both sides of the argument and, if possible, to 

 adopt a position which will favor and not forestall further investigations. 



\\ e may divide our subject into two parts and consider, first, the 

 plant adaptations that are said to indicate symbiosis, and second, the 

 ants that are associated with plants. The supposed adaptations may be 

 considered under two heads: the dwelling places and the food 'provided 

 for the ants. The former consist either of preformed cavities or of 

 structures from which the pith or loose tissue can be easily removed 



