Physiology of Central Nebvous System 71 



5. We must also deprive the ganglion-cells of all specific 

 significance in spontaneous movements, just as we have done 

 in the case of simple reflexes and instincts. By spontaneous 

 movements we mean movements which are apparently deter- 

 mined by internal conditions of the living system. Strictly 

 speaking, no movements of animals are exclusively determined 

 by internal conditions, for atmospheric oxygen and a certain 

 range of temperature are always necessary in order to preserve 

 the activity beyond a short period of time. 



We must discriminate between simple and conscious spon- 

 taneity. In simple spontaneity we must consider two kinds 

 of processes, namely, aperiodic spontaneous processes and 

 rhythmically spontaneous or automatic processes. The rhyth- 

 mical processes are of importance for our consideration. 

 Respiration and the heart beat belong in this category. The 

 respiratory movements seem to indicate that automatic 

 activity can arise in the ganglion-cells, and from this the con- 

 clusion has been drawn that all automatic movements are due 

 to specific structures of the ganglion-cells. Recent investiga- 

 tions, however, have transferred the problem of rhythmical 

 spontaneous contractions from the field of morphology into that 

 of physical chemistry. The peculiar qualities of each tissue are 

 partly due to the fact that it contains certain ions (Na, K, Ca, 

 and others) in definite proportions. By changing these pro- 

 portions, we can impart to a tissue properties which it does not 

 ordinarily possess. If in the muscles of the skeleton the Na 

 ions be increased and the Ca ions be reduced, the muscles are 

 able to contract rhythmically like the heart. It is only the 

 presence of Ca ions in the blood which prevents the muscles 

 of our skeleton from beating rhythmically in our body. As the 

 muscles contain no ganglion-cells, it is certain that the power of 

 rhythmical spontaneous contractions is not due to the specific 



the contraction ol one group of muscles necessitates the stretching of their antago- 

 nists the coordinated character ol locomotive action seems to become intelligible 

 (1912). 



