TENSION PHENOMI NA OF LIVING ELEMENTS. 



Experimental. 



Platinum electrodes, platinized with platinic chloride contain- 

 ing a little lead acetate, and of a form similar to those designed 

 by r.aleotti, were used. Galeotti stimulated tin- muscle through 

 the same electrodes used in measuring the electric conducmity, 

 by -\\iiching on a different electric current. Though it were 



-iblc to throw a switch quickly enough to have the curivm 

 for inea-iireinent of conductivity pass through the muscle 

 during contraction, it would be necessary to use a string u.il- 

 \ -.mom! -it -r to take the reading, and this method would probably 

 noi b<- very accurate. A more accurate method is that of Kohl- 

 IMII-I li, in which a rapidly alternating current reduces polari/atioii 

 at the electrodes and in the tissue, but it is necessary to throu the 

 nni-cle into tetanus in order to have time for the reading. I 

 a< Miiipli-lu-d this by using the same current for stimulation and 

 inra-mvmein of conductivity. A very small induction coil wa- 

 luted \\itli a rheostat in the primary. Another rheostat in the 



-e ilaiA could l>e thrown out of the circuit by a s\\itch. By 



adjiMini; ihr rheostats, a current strong enough to be dis- 

 tiiu tlv heard in the telephone, yet too weak to stimulair the 

 nm-cle, \\a- obtained. By switching the resi-tance out of the 



ondarj > in nit, the current could immediately be im-iva-rd so 

 a- to thiou the muscle into tetanus. Since the \Vhrai-tonr 

 britlg* \\a^ u->ed, the difference in current strength- had no <lii 

 effect "ii tht- readings. The conducti\ it\ increa-nl from o to 

 28 per cent, (being usually about 15 per cent.) on stimulation. 

 \Ye ha\c, then, evidence for the increase in prrnu-ability of 

 muscU- to ions during contraction, but what relation has this 

 to tin- mechanism of the contractile process? It has been su-- 



;rd by D'Arsonval, Ouincke, Imbert, P.t rn-t ( in, (ialeotti 

 ami others that the increased permeability to ion-, causes a dis- 

 appearance of the normal electrical polari/ation of the elements, 

 surface tension consequently increases, cau-ing them to 

 up (shorten). But what are the elements concerned:' 

 It would be confu-ing to assume them to be the fibers, as then the 

 function of the complicated internal structure would be mu\- 

 plained. They are probably not the sarcous elements (por- 

 tions of fiber bet \\een 2 Z-lines) as the rounding up of these ele- 



