12 GENERAL PRINCIPLES OF ZOOLOGY. 



species of animals there was no lack of material, and so the arena 

 was opened for that spiritless zoology of species-making which in 

 the first half of the last century brought zoology into such discredit. 

 Zoology would have been in danger of growing into a Tower of 

 Babel of species-describing had not a counterpoise been created in 

 the strengthening of the physiologi co-anatomical side. 



DEVELOPMENT OF MOKPHOLOGY. 



Anatomists of Classic Antiquity. Comparative anatomy for 

 this chiefly concerns us here for a long time owed its development 

 to the students of human anatomy; this is due to the fact that even 

 up to a recent date comparative anatomy was assigned to the 

 medical faculty, while zoology belonged to the philosophical 

 faculty, as if it were an entirely separate study. The disciples of 

 Hippocrates had previously studied animal anatomy for the pur- 

 pose of obtaining an idea of human organization, from the struc- 

 ture of other mammals, and thus to gain a secure foundation for 

 the diagnosis of human diseases. The work of classical antiquity 

 most prominent in this respect, the celebrated Human Anatomy 

 by Claudius Galenus (131-201 A.D.), is based chiefly upon obser- 

 vations upon dogs, monkeys, etc. ; for in ancient times, and even 

 in the Middle Ages, men showed considerable repugnance to 

 making the human cadaver a subject of scientific investigation. 



Middle Ages. The first thousand years in which Christianity 

 formed the ruling power in the mental life of the people was quite 

 fruitless for anatomy; in the main men held to the writings of 

 Galen and the works of his commentators, and seldom took occa- 

 sion to prove their correctness by their own observations. With 

 the ending of the Middle Ages the interest in independent scien- 

 tific research first broke its bounds. 



Vesal (1514-1564), the creator of modern anatomy, had the 

 courage carefully to investigate the human cadaver and to point 

 out numerous errors in Galen's writings which had arisen through 

 the unwarranted application to human anatomy of the discoveries 

 made upon other animals. By his corrections of Galen, Vesal was 

 drawn into a violent controversy with his teacher, Sylvius, an 

 energetic defender of Galen's authority, and with his renowned 

 contemporary Eustachius, which did much for the development of 

 comparative anatomy. At first animals were dissected only for 

 the purpose of disclosing the cause of Galen's mistakes, but later 

 through a zeal and love for facts. It was natural that first of all 



