30 
such contifiifous excitation does take place during the passage 
of the polarising current is a conclusion definitely arrived at 
by Biedermann. He says : — "The electrical current sets up a 
process of excitation in striated, as in smooth, muscle 
throughout the duration of its passage.""^ Assuming, for the 
moment, what is about to be proved, namely, that the setting 
free of kations by the current is the cause of contraction, we 
see that the fact that maximal twitches are much higher with 
a constant than with an induced current! is due to the 
greater amount of decomposition of kation-proteid by the cur- 
rent v/hich acts the longer time. 
As to the nature of the kations which form the ion-proteid 
in the hyaloplasm of striated muscle, we can say very 
little. The effects of chemical re-agents on muscle show, as 
we shall see later, that simple metallic ions are capable of 
forming ion-proteids in muscle just as in unicellular organ- 
isms. Probably K and H ions play an important part — as 
it is well known that KH^PO^ is always formed when muscle 
becomes rigored — and, moreover, K salts predominate in the 
ash of muscle, Ca and Mg only being present in traces. | 
Now, it is evident that, since hyaloplasm is laden with 
kation-proteid, the result of its katabolism or dissociation 
must be the formation of an electrical double layer at the 
contact surface of the hyaloplasm and spongioplasm by the 
deposition of ions, just as in the case of the contact surface 
between the mercury and sulphuric acid solution in the capil- 
lary electrometer. 
The action of a stimulus, such as an electric current, on 
muscle, is to set up katabolism at certain points in the 
muscle (c.(/., the kathode on make), and the consequence of 
this is, as we have seen, to cause "negativity" at such points 
in consequence of the kations set free. This "negativity" is 
transmitted, practically unaltered, § along the muscle, and its 
mode of transmission will be discussed in detail in the sequel. 
It remains to consider the effect of the progress of this 
area of high potential along the muscle. It will be, as ex- 
pressed by Bernstein's "wave of excitation," || to uninterrup- 
* Biedermann : Electro-physiology : Trans, by F. A. Welby, 
vol. i., page 185. 
t Ihi(]., vol. i., page 176. 
t Starling: Elements of Human Physiology, fifth edition, 
page 130. 
§ BiedeTTnann : Electro-physiology: Trane. by F. A. We^by, 
vol. i., page 395. 
II Ibid., vol. i., piage 374. 
