406 PHYSIOLOGY 



chemistry of the organism, arises of itself the extremely close connec- 

 tion with these two general natural sciences. Physics and chem- 

 istry ascertain the general laws which rule the perceptible world, 

 and physiology analyzes the action of these laws in the special system 

 of the organism, as geology studies the activity and force of gen- 

 eral physical and chemical principles in the special system of the 

 planets, or mineralogy in the special system of crystals and minerals. 



The organism is, therefore, for the physiologist, only a special 

 case of a system, which he must analyze according to the general 

 principles of physics and chemistry. Physiology, therefore, receives 

 from physics and chemistry its general conception of the laws of 

 phenomena in the physical world. The more deeply physics and 

 chemistry penetrate into the knowledge of general laws, so much 

 more deeply can the investigation of the phenomena of life proceed. 

 Physiology is, in this relation, entirely dependent upon the develop- 

 ment of physics and chemistry, and must follow their progress 

 attentively. To-day this is especially important. The rapid devel- 

 opment of the great mass of facts and theories, which have recently 

 been united under the name of "physical chemistry," appears to 

 be destined to unite these previously independent sciences to a 

 uniform scientific branch. A number of theories of a general nature 

 have already been proposed which must have a marked influence 

 on the investigation of the phenomena of life. The effect of this 

 great progress in the realm of physical chemistry is already begin- 

 ning to be felt in physiology. The recent conceptions regarding the 

 nature of solutions, the theory of ions, the conception of osmosis 

 and diffusion and of electrochemical processes, the knowledge of 

 the laws of chemical equalization and the effect of mass, and many 

 other new ideas, are already beginning to have as fruitful an influ- 

 ence upon the investigation of the phenomena of life as a half- 

 century ago the discovery of the laws of energy exercised. 



But the conception and symbols of physics and chemistry 

 will be still further developed, and will be materially changed, in 

 the course of time. We live to-day in a period in which the well- 

 proved symbols of physics and chemistry, hoary with age, such as 

 the conception of matter, of atoms, and of force, begin to waver. 

 New symbols, new allegories, new conceptions will come in their 

 place. It would, therefore, be illogical to expect that physiology 

 could solve all the phenomena of life without fail, by the present 

 knowledge of physics and chemistry. It is still far away from this 

 goal. Physics and chemistry cannot explain quite all of the simpler 

 phenomena of the lifeless natural world, with their present symbols. 

 But however the conceptions of physics and chemistry may change 

 in the course of time, one fact remains: no other principles can come 

 into play in the world of organisms than enter into that of lifeless 



