PREFACE. 



IN the translation of this work and the preparation of an 

 American edition an effort has been made to place at the com- 

 mand of English-speaking instructors and students a text-book 

 which includes the best results of recent investigations. The 

 spirit and characteristic features of the German original have 

 been carefully retained, changes in text or illustration being 

 made only where some definite advantage was to be attained. 

 These changes have mostly resulted in enlargements. Thus 

 ten of the German engravings have been replaced with thirty- 

 five new ones, taken from various sources. These can be 

 identified by the credits given in connection with the respec- 

 tive figures. Many additions have likewise been made in the 

 text. I am especially indebted to Dr. Florence R. Sabin for 

 a brief description of the medulla and midbrain. 



Nearly all of the drawings which have been taken from the 

 German edition were made by Dr. Baracz from material pre- 

 pared by the author, who acknowledges the assistance also of 

 Dr. Bochenek, Professor Browicz, and Dr. R. Krause. 



It has. been my object throughout to trace, as far as pos- 

 sible, the development of the organs and the histogenesis of 

 the tissues, and it is hoped that the attention of instructors and 

 students may be drawn to the importance of viewing Histology 

 from this standpoint. I have endeavored, also, to emphasize 

 the fact that in many organs it is possible to recognize struct- 

 ural units which are repeated in a definite way arid bound 

 together by a characteristic framework. 



I nrn much indebted to Professor F. P. Mall for the kind 

 interest he has taken in the preparation of this edition. 



JOHN BRUCE MACCALLUM. 



BALTIMORE, July, 1902. 



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