PREFACE. 



IN his work on the " Human Species," Hopf compares 

 the structure, functions and diseases of man with those 

 of animals. It must not be taken, however, that the 

 volume is simply a collection of facts and details. A 

 glance at the headlines of the pages will reveal the wide 

 extent of the ground covered. After discussing the 

 distribution of mankind, the ancestors of man, the struc- 

 ture and functions of the various tissues, Hopf deals 

 with such interesting questions as psychology, the 

 origin of the mind, emotions and their expression, social 

 customs, marriage, communism, modesty, shame, religion 

 and art. He then proceeds to consider the diseases of 

 man and animals, the parasites common or peculiar to 

 each, .and concludes with a fascinating chapter on self- 

 help in animals and primitive man. Realising that such 

 aspects of the subject will appeal to the general reader, 

 the text has been shorn of scientific terminology as 

 much as possible. 



In preparing an English translation the Editor has 

 tried to follow out the general idea of the author, 

 and therefore no apology is needed for the terminology 

 employed. Difficulties have arisen in adapting the 

 German classification to the English reader, and in 

 some instances it has been necessary to retain terms and 

 distinctions not usually current in English books. A 



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