48 GENERAL PHYSIOLOGY 



they are not the end-results of vital activity. All that we are 

 now accomplishing by means of the special methods that were 

 created by the great masters of physiology for this purpose, is 

 essentially only an extension of our present knowledge into finer 

 details, and its application to analogous conditions. Every glance 

 into physiological literature proves this. Every new number of 

 the journals shows it. At present there is no dominating 

 tendency in physiology, such as was the physical tendency a short 

 time ago. A new great discovery is made along the present path 

 only rarely, in spite of a frequently marvellous employment of 

 ingenuity and knowledge, and yet the real riddles of life are not 

 yet solved. We would not go so far as Bunge goes, and maintain 

 that all phenomena which thus far have been explained mechanically 

 are not vital phenomena at all ; but there can be no doubt that 

 thus far we have not been able to explain the general, the 

 elementary, vital phenomena. This impotence of the physiology 

 of to-day in the presence of the simplest vital processes points 

 plainly to the fact that the methods that have explained the mecha- 

 nics of gross and special physiological activities, however ingeniously 

 they were devised for that purpose, fail for other purposes, for the 

 investigation of the elementary and general activities. 



In order to solve the elementary general problem we must take 

 a wholly different path. There is only one such path, and it was 

 clearly indicated when the facts in the history of physiological 

 research were summarised. Consideration of the individual 

 functions of the body urges us constantly toward the cell. The 

 problem of the motion of the heart and of muscle-contraction 

 resides in the muscle-cell : that of secretion in the gland-cell ; 

 that of food-reception and resorption in the epithelium-cell and 

 the white blood-cell ; that of the regulation of all bodily activities 

 in the ganglion-cell. The cell-theory has long shown that the cell 

 is the structural element of the living body, the elementary 

 organism in which the vital processes have their seat. Anatomy, 

 embryology, zoology, and botany have long recognised the signi- 

 ficance of this fact, and the great achievements of these sciences 

 are a brilliant proof of the fruitfulness of the cell-method of 

 investigation. But only very recently has the simple and plainly 

 logical consequence begun to be recognised that, if physiology 

 considers its task to be the investigation of vital phenomena, it 

 must investigate them in the place where they have their seat, i.e., 

 in the cell. If it is not to be content with extending still farther 

 the present knowledge of the gross activities of the human body, 

 but would really explain elementary and general vital phenomena, 

 it must assume the character of cell-physiology. 



It might appear paradoxical that thirty-five years after Rudolf 

 Virchow ('58) expounded, in his Celhdarpathologie, the cell 

 principle as the basis of all organic investigation- a basis upon 



