196 Conclusion. 



aprioristic postulates of modern evolutionism, 1 accord- 

 ing to which man is nothing but the highest brute, 



*) We cannot enter here on the general question of the develop- 

 ment of instincts. Cf. for this purpose my former publications: "Die 

 Entstehung der Instincte nach Darwin" ("Stimmen aus Maria-Laach," 

 XXVIII, 333), "Die Entwicklung der Instincte in der Urwelt" (ibid. 

 XXVIII, 481; XXIX, 218, 383); "Zur Entwicklungsgeschichte der 

 Ameisengesellschaften" ("Die zusammengesetzten Xester und gemischten 

 Kolonien der Ameisen," III section, 2 Chap.). 



As to the explanation of the genuine guest-relationship (symphily) 

 by the Darwinian theory of evolution cf. "Zur Entwicklung der In- 

 stincte" ("Verhandlgn. der Zoolog. Botan. Gesellsch.," Wieti, 1897, 3d 

 issue 1 , pp. 168-183). Of late Dr. K. Escherich has tried to solve the 

 contradiction, which we proved to exist between the facts of 

 symphily and the principles of natural selection ("Zur Anatomie und 

 Biologic von Paussus turcicus, Zugleich ein Beitrag zur Kenntnis der 

 Myrmekophilie," in "Zoolog. Jahrbuecher" Abth. fuer Systematik, XII, 

 1898, 27-70). He insists that symphily is not a separate instinct 

 totally different from the breeding instinct of ants, but that the two are 

 in causal relation to each other. We formerly (see the first German ed. 

 of present essay, p. 107 below, and p. 108 above) pointed out the same. 

 Yet Escherich is wrong in believing that natural selection has been 

 unable to prevent the development of symphily in spite of the damage 

 done by it to the ants, because symphily is so closely connected with 

 the breeding instinct. Natural selection must counteract not only the 

 development of an entirely new instinct which proves injurious to the 

 possessor, but also the extension to injurious objects of an already 

 existing useful instinct; hence selection was just as little allowed to let 

 the breeding instinct of ants extend its activity to Lotnechusa, Atemeles, 

 Paussus and other noxious objects, as it was allowed to let the feeding 

 instinct of animals extend its activity to palatable but poisonous herbs 

 or to nutritious plants covered with parasites. (Cf. "Die psychischen 

 Faehigkeiten der Ameisen," 1899, p. 124.) To this Escherich again 

 objected (in "Zool. Centralbl.," 1899, No. 1, p. 17), that many sheep 

 are killed by feeding on plants covered by "cercaries" ('. e., the 

 capsulate form of undeveloped trematodes). But what would Mr. 

 Escherich say to the following, if within the whole species of sheep, 

 or within a certain race of them, there should develop a special liking 

 for feeding on plants covered by those parasites? Would not such a 

 phenomenon evidently contradict the theory of natural selection? But 

 this is exactly the case with the rearing of Lomechusas by the 

 sanguine slave-makers. Therefore Escherich's objections but confirm 

 the truth of our assertion: The fact that ants by nursing their guests 

 rear their greatest enemies, is equally incompatible with the principles 

 of natural selection and u-ith the principles of modern animal psychology. 



