PEEFACE BY PROFESSOR ERNST HAECKEL 



THE morphology of the animal body, which is the subject of the 

 following excellent text-book, has been, during the last forty years, 

 i.e. since the commencement of my academic career, the favourite 

 object of my scientific labours. During these four decades no other 

 science has undergone such profound and striking transformation. 



In the years 1852-1856, when I attended in Berlin and Wiirzburg 

 the masterly anatomical and zoological lectures of Johannes Miiller, 

 Albert Kolliker, and Franz Leydig, the study of comparative anatomy 

 and of comparative histology had been brought into great prominence 

 through Miiller's classical researches in the former, and Leydig's in 

 the latter field. 



Oscar Schmidt's text-book of comparative anatomy which resulted 

 from the transcription of. Johannes Miiller's summer lectures, and 

 passed through eight editions, gives evidence of the stage then reached 

 by that science. Upon this work the present text-book of Professor 

 Arnold Lang is founded, as its ninth edition ; the present state arid 

 needs of the science, however, compelled the new editor to rewrite 

 the whole book on a much larger scale. 



Johannes Miiller, the great master in the domains of comparative 

 anatomy and physiology, died in 1858, after having held sway as the 

 leader in these sciences for more than quarter of a century. This 

 very year 1858 saw the simultaneous publication by Charles Darwin 

 and Alfred Wallace of their preliminary sketches of the Theory of 

 Selection. The year after appeared the Origin of Species, which at one 

 stroke ushered in, by means of this theory, a new epoch for the 

 biological sciences. 



