16 GENERAL PHYSIOLOGY 



ing in the history of science, systems appeared at that time as 

 evidence of a reaction against excessive specialisation, which fell 

 into the opposite extreme of lacking all exact foundation and 

 resting upon pure speculation. Boerhaave (1668-1738) skilfully 

 avoided this pitfall in his eclectic system, which was put together 

 from the various dogmas of his time and assumed as the source of 

 all vital phenomena a "principiwni nervosum " in the form of a very 

 subtile fluid. But the systems of Hoffmann (1660-1742) and of 

 Stahl (1660-1734) did not escape it. Hoffmann's "mechanico- 

 dynamical " system is purely teleological. and arose under the 

 influence of the philosophy of Leibnitz. Hoffmann regarded the 

 ether as the ultimate cause of all vital phenomena ; its movement 

 follows mechanical principles, but it receives its immediate impulse 

 from the idea of the purpose of its own existence, that resides in 

 every ether-atom. But Stahl's " animistic system," which com- 

 bated Hoffman's doctrines, rests still more upon a speculative 

 basis. At the foundation of Stahl's system there lies a dualism of 

 body and mind, according to which the body in its activities follows 

 mechanical laws, but is animated and preserved from decay and 

 destruction by the " anima." Upon the nature of the anima Stahl 

 expresses himself in very uncertain and contradictory terms. In 

 spite of its unsupported speculations and its many contradictions,, 

 animism obtained numerous adherents, which may be explained by 

 the facts that the innumerable details acquired by the many special 

 researches of the period were not properly sifted, and there was. 

 no coherent understanding of vital phenomena. 



D. THE PERIOD OF HALLER 



Haller (1708-1777) responded in a genuinely scientific manner to 

 the need of a unitary arrangement of the details, and, as it had 

 once been with Galen and, later, with Harvey, a new epoch in the 

 development of physiological investigation dates from his appear- 

 ance. As Galen had first recognised the practical significance of 

 physiology and had made the knowledge of vital phenomena the 

 basis of practical medicine, and as Harvey by the introduction of 

 exact experimental investigation had created the fruitful method, 

 the employment of which in the sixteenth and seventeenth centuries 

 called forth the enormous mass of individnal discoveries, so Haller 

 for the first time brought together as a whole all the extensive 

 material of facts and theories in his " Memento, physiologiac 

 corporis humani." He thus made physiology an independent 

 science, which was not simply to serve practical purposes in the 

 interest of the art of healing but also to pursue purely theoretical 

 aims for itself alone. 



In this circumstance lies Haller's great importance in the 

 development of physiology. The grouping of a heterogeneous- 



