308 ROBERT M. YERKES 



their ' reason.' This is not a severe reproach to Alfred Brehm when one remembers 

 how general, at that time, was the humanizing of animals, even among scholars. 

 Nor is it to be regretted for Brehm's briUiant success in winning for the animal 

 world that cordial interest of readers, most of whom had never troubled them- 

 selves about it before, was certainly due in large part to this very humanizing. 

 Nowadays we know, that with the intelligence of animals in doubtful status, almost 

 all of their wonderful performances can be explained in a simpler manner; by 

 associated impressions of the circumstances accompanying their favorable and 

 harmful experiences, or mostly even as inborn instincts. And since even now we 

 do not know any means of judging about the ' feelings ' and other mental processes 

 of animals, it is better to remain silent concerning them. This modern point of 

 view must be taken as the basis in a new edition of ' Brehm.' This is not equivalent 

 to saying that the new ' Tierleben ' will be any less sympathetic, or that the use 

 of it by the laity, or even by children, will be less attractive; on the contrary, the 

 wonderful purposefulness and perfection of the animal instincts, and the often- 

 times amazing way in which apparently intelligent acts may be simply explained, 

 probably will be more captivating for the present-day reader of ' Brehm ' than 

 the earlier humanizing. 



" It therefore became clear that so far reaching a transformation as the one 

 planned could not be effected by one person alone; the work must be divided. 

 That delightful writer, the Director of the Zoological Garden of Berlin, Professor 

 Ludwig Heck, undertook the revision of the ' Mammals,' which he knows so thor- 

 oughly. Professor (Doctor) William Marshall, the widely beloved author of ' The 

 Walks of a Xaturalist ' — who died in the midst of the task — turned over for the 

 division on ' Birds ' the rich material which he had been gathering for years toward 

 a great ornithological work. For the ' Reptiles and Amphibians ' the well-known 

 specialist. Doctor Franz Werner, Professor in the University of Vienna was secured. 

 ' Fishes ' was undertaken by Doctor Otto Steche, privat docent at Leipzig, who 

 has worked upon it at home and carried it with him in his journey around the 

 world. Professor (Doctor) Richard Heymons of Berlin revised the volume 'Insects,' 

 in which the spiders and millipeds are included. With each of these groups this 

 scholar is thoroughly acquainted through his own investigations. The revision 

 of the remaining ' Invertebrates ' I undertook myself. 



' Especial attention has been given to the illustrations — ^always a noted feature 

 of the ' Tierleben.' In this it was worth while to take advantage of the modern 

 processes of reproduction." 



To condense the remaining page of the preface — no pains 

 were spared to obtain accurate, realistic, and artistic drawings. 

 Skihed artists were employed, who, in certain instances, made 

 drawings from life in Africa, x\sia, various parts of Europe, 

 and England. 



The new " Tierleben," of which at present the sixth volume, 

 " Birds," has appeared, will stand as the authority among 

 natural histories of animals. It is highly desirable that it be 

 translated into English. 



