192 



COMPARATIVE PHYSIOLOGY. 



Fig. 180. — Representation of electrical currents in a mnscle-rliombus (after Rosenthal). 



strength, according to the parts of the muscle connected hy the 

 electrodes. The strongest is that resulting when the superfi- 

 cial equator and the transverse center are connected ; and it is 

 found that the nearer these points are approached the stronger 

 the current hecomes. 



It is important to note that the electric current of muscle, 

 however viewed, is associated with the chemical and all the 

 other molecular changes of which the actual contraction is 

 hut the outward and visible sign ; and since the currents have 

 ■ an appreciable duration, wane with the vitality of the tissue, 

 and wholly disappear at death, they must be associated with the 

 fundamental facts of organic life ; for it is to be remembered 

 that electrical currents are not confined to muscle, but have 

 been detected in the developing embryo, and even in vegetable 

 protoplasm. Though the evidence is not yet complete, it seems 

 likely that electrical phenomena may prove to be associated 

 with (we designedly avoid any more definite expression) all 

 vital phenomena. 



Chemical Changes in Muscle.— At a variable period after 

 death the muscles become rigid, producing that stiffness {rigor 

 mortis) so characteristic of a recent cadaver. 



