CHAPTER X 
VON BAER AND THE RISE OF EMBRYOLOGY 
ANATOMY investigates the arrangement of organic tissues; 
embryology, or the science of development, shows how they 
are produced and arranged. There is no more fascinating 
division of biological study. As Minot says: ‘Indeed, the 
stories which embryology has to tell are the most romantic 
known to us, and the wildest imaginative creations of Scott 
or Dumas are less startling than the innumerable and almost 
incredible shifts of réle and change of character which 
embryology has to entertain us with in her histories.” 
Embryology is one of the most important biological sci- 
ences in furnishing clues to the past history of animals. 
Every organism above the very lowest, no matter how com- 
plex, begins its existence as a single microscopic cell, and 
between that simple state and the fully formed condition 
every gradation of structure is exhibited. Every time an 
animal is developed these constructive changes are repeated 
in orderly sequence, and one who studies the series of steps 
in development is led to recognize that the process of 
building an animal’s body is one of the most wonderful 
in all nature. 
Rudimentary Organs.—-But, strangely enough, the course 
of development in any higher organism is not straightforward, 
but devious. Instead of organs being produced in the most 
direct manner, unexpected by-paths are followed, as when 
all higher animals acquire gill-clefts and many other rudi- 
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