Architecture in the Animal Kingdom. 99 



rhachis build their nests on trees by sewing together 

 clusters of leaves. It is now finally ascertained (see 

 p. 128-129), whence the Oecophylla procure the 

 material for their threads. They do not secrete it 

 from their mandibular glands, as was hitherto sup- 

 posed/ but they use their young larvae as "spinning- 

 wheels," moving them to and fro between the edges oi 

 the leaves. This strange fact observed already by 

 Ridley and Holland^ has recently been confirmed by 

 other scientists. 



Another class of ant nests, likewise found in the 

 tropics exclusively, are the natural cavities in the 

 stems, thorns and bladder-shaped swellings of the so- 

 called '*ant-lodging plants," which invite ants to take 

 possession of their well furnished lodgings. Several 

 of these plants, ab the American Imbauba (Cecropia 

 adenopus) offer to the ants, besides the lodging, also 

 an agreeable food in the form of special honey-bearing 

 nectaries. In return for their kindness the "ant-lodg- 

 ing plants" are afforded by their valiant lodgers effec- 

 tive protection against leaf-cutting ants and other 

 herbivorous insects.^ This mutual relationship of the 

 ants with the plants in question is called Symbiosis 

 (consociation). It bears, in fact, some similarity to the 

 associations existing between animals of different 



^) E. H. Aitken, "Red Ants Nests" ("Journal of the Bombay Nat. 

 Hist. Soc.," 1890, Vol. V, n. 4, p. 422), also Forel, "Die Nester der 

 Ameisen" (Zuerich, 1892), p. 19. 



2) J5. E. Green, "On the Habits of Oecophylla smaragdina F." 

 ("Proceedings Entomol. Soc. of London," 1896, p. IX.) 



') Frits Mueller, "Die Imbauba und ihre Beschuetzer" ("Kosmos," 

 VIII, 109), and A. F. W. Schimper, "Die Wechselbeziehungen zwischen 

 Pflanzen und Ameisen im tropischen Amerika" (Jena, 1888). Also 

 H. V. Jhering, "Die Ameisen von Rio Grande, do Sul," in "Berl. 

 Entom. Zeitschr.," 1894, 3d issue, p. 354 and 364 ff. 



