CHAPTER XXII. 



TRUE GUESTS, ECTO- AND ENTOPARASITES. 



" Es gibt wohl \\enige Gebiete der Zoologie, wo Morphologic and Biologic 

 sich so nahc beriihren, so innig durchdringen uncl sich gegenseitig so erganzen 

 \vie hier: die Biologic erschliesst erst das voile Verstandniss der betreffenden 

 morphologischen Charaktere, und andercrseits lassen die morphologischen Cliar- 

 akterc uns oft bereits die Biologic jener Wesen vorauserkennen und gebcn uns 

 die \\ ichtigsten Winke fur die Erforscbung derselben." Wasmann, " Die Myrme- 

 kophilen und Termitophilen," 1896. 



The persecuted and tolerated guests described in the last chapter 

 are merely the plebeian precursors of the aristocracy among the myrme- 

 cophiles, the 300 or 400 true guests, which are no longer content to 

 be treated with animosity or indifference, but have acquired more inti- 

 mate and even friendly relations with the ants. These true guests are 

 not, therefore, to be found skulking in the unfrequented galleries of 

 the nest, or suspiciously dodging about among the ants, but live in their 

 very midst with an air of calm assurance, if not of proprietorship. As 

 a rule, they have abandoned such indefinite or panmyrmecophilous 

 attachments as those of the synoeketes and have settled down to asso- 

 ciations with particular host species or genera. The ants, however, still 

 remain the passively exploited partners of the alliance ; they become, in 

 fact, only the more easily mulcted and despoiled as the symbiotic inti- 

 macy increases, till, in some cases, they seem to be suffering from a 

 social obsession or disease like the alcoholism of human communities. 

 It is but a step from these true guests, or symphiles, to the parasites 

 in the restricted sense. Some have regarded the symphiles, like the 

 synechthrans and the synoeketes, as parasites on the ant colony, in 

 contradistinction to the ecto- and entoparasites, which exploit the indi- 

 vidual ant or ant larva, but this, as we shall see, is a somewhat artificial 

 distinction. 



The Symphiles. These are very largely beetles, and though they 

 belong to many different families, they show a remarkable adaptive 

 convergence, for in order to solicit food from the ants and ingratiate 

 themselves by means of peculiar exudations, they have developed the 

 following peculiarities in coloration, in the structure of glands, mouth- 

 parts and antennae: 



i. Syutpliilic Coloration. Wasmann has called attention to the 

 peculiar red color and oily surface characteristic .of many true guests. 



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