12 THE HYPOTHESIS AND THEORY OF 



wing-cases, which have been admitted as guests by the 

 wandering ants and the slave-keeping ants. The guests of 

 these ants can be divided into three biological classes : (1) 

 the true guests, the most interesting type of which is an 

 African species named SympoleTnon a-nommatis. As an 

 example of the second class, a photograph was shown of a 

 brachyopteron known as the Mimeciton pulex, or ant-ape, 

 which lives among the blind wandering ants of Brazil, and is 

 enabled to pursue its parasitic existence through bearing a 

 remarkable resemblance to the ants in the form of its an- 

 tennae and of its whole body. The ants' sense of touch in 

 their antennae is deceived by this resemblance. In con- 

 nection with this subject of mimicry, other illustrations 

 were given. As representing the third biological class, the 

 lecturer displayed a photograph of the so-called hostile type 

 (Trilobitideus, etc.) in which the beetle is protected by a 

 shell against any attack on the part of ants. These 

 creatures have been evolved out of the same family of 

 Brachyoptera, although in form they differ from one another 

 more than an ape differs from a tortoise. The same final 

 result might be produced by very various methods of 

 adaptation; so in some cases synechthry has led to the 

 development of a genuine guest relation, which in other 

 cases is due to mimicry. 



A series of photographs illustrated the highly interesting 

 evolution of Pselaphidae to Clavigeridse. All true inquilines 

 have organs of exudation, developed in a greater or less 

 degree, which emit an aromatic substance that the ants 

 enjoy licking, and it is in order to obtain it that they feed 

 their guests. The formation of these organs of exudation is 

 particularly interesting in the case of certain Paussidae, 

 which are allied to the Carabidae, or ground-beetles. Their 

 antennae have been transformed into veritable cups con- 

 taining a sweet fluid. The theory as to the origin of slavery 

 among ants was explained by another series of photographs, 

 at the conclusion of which was a picture of a peculiar 

 parasitic ant (Anergates atratulus), which possesses no real 

 workers, but only winged females and wingless, strangely 



