in ELECTRICAL EXCITATION OF MUSCLE -2i>7 



anode, extending over a large area; in individual cases (intestine, 

 muscular integument of worms, -ureter) this gives the impression tlml 

 tin- make excitation proceeds entirely and chiefly from the anode, a 

 view that has already been expressed lij Joft with regard to lln- 

 intestine (34). 



It may be questioned if there is any analogue to this reaction 

 in striated skeletal muscle. But before entering on this dis- 

 cussion, it will be advisable to go a little more closely into the 

 allied, and from various points of view highly interesting, pheno- 

 mena in cardiac muscle (35). Since the heart alternates rhythmic- 

 ally between contraction and relaxation, we are able to test the 

 action of the current in both phases. It is advisable to use the 

 heart of a cold-blooded animal, beating as slowly as possible e.g. a 

 large and well-cooled frog. If two fine brush electrodes are then 



o o 



applied to the surface of the ventricle at two parts as wide apart 

 as possible, with persistent closure of a sufficiently strong battery 

 current, a very striking result will ensue. At each new systolic 

 contraction a local relaxation of the ventricle appears at the 

 anode during closure of the current, in the form of a dark- 

 red, blistered swelling ; while 011 opening the current, on 

 the other hand, the kathodic area is invariably first to relax 

 during one or several systoles, presenting an appearance exactly 

 similar to the anode during closure. These manifestations can 

 be still better investigated with the unipolar method of excita- 

 tion, one unpolarisable brush electrode being placed on any indif- 

 ferent point, e.g. the skin of the throat, while the other, a finely 

 pointed contact, is applied to the ventricle, in such a way that 

 the circuit is never interrupted while the heart is in motion, with- 

 out undue pressure. The effects vary according to the strength and 

 direction of the current, and the condition of the heart-muscle at the 

 moment of excitation. If the current enters by the electrode in 

 contact with the ventricle, and closure is effected at the beginning 

 of the systole, the first result of weak excitation (1 Dan., rheochord 

 resistance 20, or more) will regularly be relaxation at the 

 point of contact and its immediate proximity, repeated at 

 each new systolic contraction as long as closure of the current 

 continues. With increasing intensity of current there is a corre- 

 sponding increase in the degree and amplitude of the relaxation, 

 which at first is strictly local, standing out from the pale, con- 

 tracted, surrounding area as a little red speck, scarcely 1 mm. in 



s 



