Preface to the First Edition. 



difference, that exists between the sense organs and 

 the nervous system of Arthropods on the one hand and 

 of Vertebrates on the other, is not a sufficient a priori 

 reason for ascribing intelligence to the latter only and 

 denying it to the former. The proof of these asser- 

 tions forms the groundwork of the present essay. We 

 shall compare more at length the psychic life of the 

 most "intelligent" Arthropods, namely the ants, with 

 that of the higher Vertebrates and of man. From this 

 discussion we shall learn, whether the "missing link," 

 with which modern evolutionists hope to bridge over 

 the chasm between the instinct of animals and the 

 spiritual soul of man, is to be looked for in ants or 

 in the higher Vertebrates, or whether, in fact, it exists 

 at all. Biologists will be pleased to find that the 

 present essay contains many new observations on the 

 habits of ants and their guests. 



iv 



