1 66 RALPH S. LILLIE. 



region initiates there the same state of activity as that originally 

 excited at the region of stimulation; the region which thus 

 secondarily becomes active repeats the effect at regions beyond, 

 and so the impulse spreads. There need be no decrement in 

 this type of transmission, since an effect of the same kind and 

 degree is automatically reduplicated at each point reached by 

 the excitation-wave as it passes along the tissue. 1 In the trans- 

 mission of the influence of a growing or regenerating or otherwise 

 physiologically dominant region this reduplication is apparently 

 not present, and hence a gradient of influence or "decrement" 

 is shown. Otherwise the conditions are to be regarded as essen- 

 tially the same in both types of transmission. It is possible, 

 however, that combinations of the two may occur, giving rise 

 to intermediate conditions. 



Transmission of formative influence in development or growth, 

 and transmission of the nervous type, are thus seen, according 

 to the present theory, to be simply different manifestations of 

 the same fundamental type of phenomenon, namely the trans- 

 mission of an electrical influence associated with a flow of current 

 around the bioelectric circuit. The physiological effects depend 

 upon this current. Such a theory unifies a large number of 

 apparently diverse phenomena. Thus the connection between 

 growth processes and the assumed flow of current becomes 

 intelligible if processes of electrolysis are in fact concerned in 

 organic growth, as well as in the growth of the artificial formations 

 described above. It also accounts for the rapidity of the nervous 

 type of transmission in its most highly developed form, as pointed 

 out in my earlier papers just cited. The transmission of the 

 electrical influence through a circuit is instantaneous, whether 



1 Child assumes the existence of a decrement in the nervous type of transmission, 

 similar to that observed in the transmission of formative influence; but this assump- 

 tion seems to be unnecessary. The existence of trapped excitation-waves in rings 

 of tissue, lasting in some cases for days e. g., in the medusa Cassiopea according 

 to Mayer (cf. Amer. Journ. Physiol., 1916, Vol. 39, p. 378) proves that the impulse 

 is renewed or recreated with undiminished intensity at each region reached by it in 

 its course. In such a case there is obviously no decrement. It is now well estab- 

 lished that the " all-or-none " law holds for nerve; this fact in itself would be in- 

 compatible with the existence of a decrement, since it implies that each region 

 responds with the same degree of intensity, irrespective of the strength of the 

 stimulus. The existence of a decrement in nerve during fatigue, anaesthesia, or 

 asphyxia does not prove its existence under normal conditions. 



