FUNDAMENTAL FACTS 5 



in them only general protoplasmic qualities, unless we 

 find that the phenomena cannot be explained by 

 means of the latter alone. 



2. A further objection has been raised, that al- 

 though these reflexes occur in plants possessing no 

 nervous system, yet in animals where ganglion-cells 

 are present the very existence of ganglion-cells neces- 

 sitates the presence in them of special reflex mechan- 

 isms. It was therefore necessary to find out if there 

 were not animals in which coordinated reflexes still 

 continued to exist after the destruction of the central 

 nervous system. Such a phenomenon could be ex- 

 pected only in forms in which a direct transmission of 

 stimuli from the skin to the muscle is possible, in 

 addition to the transmission through the reflex arc. 

 This is the case, for instance, in worms and in Ascidi- 

 ans. I succeeded in demonstrating in Ciona intesti- 

 nalis that the complicated reflexes still continue after 

 removal of the central nervous system (2). 



A study, then, of comparative physiology brings 

 out the fact that irritability and conductibility are the 

 only qualities essential to reflexes, and these are both 

 common qualities of all protoplasm. The irritable 

 structures at the surface of the body, and the arrange- 

 ment of the muscles, determine the character of the 

 reflex act. The assumption that the central nervous 

 system or the ganglion-cells are the bearers of reflex 

 mechanisms cannot hold. But have we now to con- 

 clude that the nerves are superfluous and a waste ? 

 Certainly not. Their value lies in the fact that they 



